MCQ Questions – Page 173

MCQ Questions for Class 12 Physics Chapter 7 Alternating Current

January 24, 2023January 22, 2023 by Prasanna

Alternating Current Class 12 MCQs Questions with

Alternating Current Class 12 MCQ Chapter 7 Question 1.

If the rms current in a 50 Hz AC circuit is 5 A, the value of the current 1/300 s after its value becomes zero is

(A) $5 \sqrt{2}$
(B) $5 \sqrt{\frac{3}{2}}$
(c) $\frac {5}{6}$
(B) $\frac{5}{\sqrt{2}}$
Answer:
(B) $5 \sqrt{\frac{3}{2}}$

Explanation:
Here, I_rms = 5 A, n = 50 Hz and t = $\frac {1}{300}$ s
= Peak value = $\sqrt{2} I_{\text {rms }}$ = $\sqrt{2}$ x 5 = 5$\sqrt{2}$ A
Now, I = I₀ sin ωt = 5$\sqrt{2}$ sin 2πvt
= 5V2 sin2π x 50 x $\frac {1}{300}$ = 5$\sqrt{\frac{3}{2}}$ A

Class 12 Physics Chapter 7 MCQ Question 2.

An alternating current generator has an internal resistance Rg and an internal reactance Xg. It is used to supply power to a passive load consisting of a resistance Rg and a reactance XL. For maximum power to be delivered from the generator to the load, the value of XL is equal to

(A) zero
(B) X_g
(C) Q – X_g
(D) R_g
Answer:
(C) Q – X_g

Explanation:
As internal resistance of generator is already equal to external resistance R_g. So to deliver maximum power, i.e., to make reactance equal to zero, the reactance in external circuit will be – X_g. In order to deliver maximum power, the generator to the load, the total reactance must be equal to zero, i.e., X_L + X_g = 0, X_L = – X_g

Chapter 7 Physics Class 12 MCQ Question 3.

When a voltage measuring device is connected to AC mains, the meter shows the steady input voltage of 220 V. this means

(A) input voltage cannot be AC voltage, but a DC voltage.
(B) maximum input voltage is 220 V.
(C) The meter reads not v but (v²) and is calibrated to read $\sqrt{\left(v^{2}\right)}$
(D) The pointer of the meter is stuck by some mechanical defect.
Answer:
(C) The meter reads not v but (v²) and is calibrated to read $\sqrt{\left(v^{2}\right)}$

Explanation:
The voltmeter in AC circuit reads value <υ²> and meter is calibrated to rms value <υ²> which is multiplied by $\sqrt{2}$ to get V_rms. In other words, voltmeter connected to the AC main read root mean square value of
AC voltage, i.e., $\sqrt{\left\langle v^{2}\right\rangle}$

Alternating Current MCQ Chapter 7 Question 4.

When frequency of applied alternating voltage very high then

(A) A capacitor will tend to become SHORT
(B) An inductor will tend to become SHORT
(C) Both (A) and (B)
(D) No one will become short
Answer:
(A) A capacitor will tend to become SHORT

Explanation:
X_C = l/2πfC
So, as / increases, X_C becomes smaller and smaller. For very high value of f, X_C will be too small which may be considered as SHORT.

Ch 7 Physics Class 12 MCQ Question 5.

Relation between r.m.s. voltage and instantaneous voltage of an AC

(A) V₀ = V_RMS / $\sqrt{2}$
(B) V_RMS = V₀ / V₂
(C) V_RMS = 0.707 V₀
(D) Both (C) and (D)
Answer:
(D) Both (C) and (D)

Explanation:
V_RMS = V₀/$\sqrt{2}$ = O.707 V₀

Physics Class 12 Chapter 7 MCQ Question 6.

The heat produced in a given resistance in a given time by the sinusoidal current I sin cof will be the same as heat produced by a steady current of magnitude

(A) 0.707 I₀
(B) 1.4121 I₀
(C) I₀
(D) $\sqrt{I}_{0}$
Answer:
(A) 0.707 I₀

Explanation:
Heat produced by AC is Heat produced by DC is I²R

$\mathrm{I}_{\mathrm{RMS}}^{2}$ = I²R
∴ I = I_rms= I₀/$\sqrt{2}$ = 0.707 I₀

MCQ Questions For Class 12 Physics Chapter 7 Question 7.

An A.C. source is connected to a resistive circuit. Which of the following statements is true?

(A) Current leads the voltage in phase
(B) Current lags the voltage in phase
(C) Current and voltage are in same phase
(D) Either (A) or (B) depending on the value of resistance.
Answer:
(A) Current leads the voltage in phase

Explanation:
In a pure resistive circuit, current and voltage are always in phase.

MCQ Of Alternating Current Class 12 Question 8.

In which of the following circuit power dissipation is maximum?

(A) Pure capacitive circuit
(B) Pure inductive circuit
(C) Pure resistive circuit
(D) LR or CR circuit
Answer:
(C) Pure resistive circuit

Explanation:
Since in pure resistive circuit the current and voltage are in phase, the power dissipation is maximum.

MCQ On Alternating Current Chapter 7 Question 9.

To reduce the resonant frequency in an L – C – R series circuit with a generator

(A) the generator frequency should be reduced.
(B) another capacitor should be added in parallel to the first.
(C) the iron core of the inductor should be removed.
(D) dielectric in the capacitor should be removed.
Answer:
(B) another capacitor should be added in parallel to the first.

Explanation:
The resonant frequency of L-C-R series circuit is v₀ = $\frac{1}{2 \pi \sqrt{\mathrm{LC}}}$
So to reduce resonant frequency, we have either to increase L or to increase C.
To increase capacitance, another capacitor must be connected in parallel with the first.

Physics Chapter 7 Class 12 MCQ Question 10.

Which of the following combinations should be selected for better tuning of an L-C-R circuit used for communication?

(A) R = 20 Q, L = 1.5 H, C = 35 pF
(B) R = 25 Q, L = 2.5 H, C = 45 pF
(C) R = 15 Q, L = 3.5 H, C = 30 pF
(D) R = 25 Q, L = 1.5 H, C = 45 pF
Answer:
(C) R = 15 Q, L = 3.5 H, C = 30 pF

Explanation:
Quality factor (Q) of an L-C-R circuit is given by,
Q = $\frac{1}{R} \sqrt{\frac{L}{C}}$
Tuning of an L-C-R circuit depends on quality factor of the circuit. Tuning will be better when quality factor of the circuit is high. For Q to be high, R should be low, L should be high and C should be low. Therefore, option (C) is most suitable.

Class 12 Physics Ch 7 MCQ Question 11.

With increase in frequency of an A.C. supply, the impedance of a series L-C-R circuit

(A) remains constant.
(B) increases.
(C) decreases.
(D) decreases at first, becomes minimum and then increases.
Answer:
(D) decreases at first, becomes minimum and then increases.

Explanation:
The frequency vs. impedance graph of a series LCR circuit is as follows:
Alternating Current Class 12 MCQ Chapter 7
With increase in frequency, the impedance decreases at first, becomes minimum and then increases.

AC Class 12 MCQ Chapter 7 Question 12.

The sharpness of tuning of a series LCR circuit at resonance is measured by Q factor of the circuit which is given by

(A) Q = $\frac{1}{R} \sqrt{\frac{L}{C}}$
(B) Q = $\frac{1}{R} \sqrt{\frac{C}{L}}$
(C) Q = $\frac{1}{L} \sqrt{\frac{R}{C}}$
(D) Q = $\frac{1}{C} \sqrt{\frac{R}{L}}$
Answer:
(A) Q = $\frac{1}{R} \sqrt{\frac{L}{C}}$

Explanation:
Q factor of a series LCR circuit is given by Q = $\frac{1}{R} \sqrt{\frac{L}{C}}$

MCQ On Alternating Current Class 12 Question 13.

At resonance, the impedance in series LCR circuit is

(A) maximum.
(B) zero.
(C) infinity.
(D) minimum.
Answer:
(D) minimum.

Explanation:
Impedance of a series LCR circuit is Z = $\sqrt{\mathrm{R}^{2}+\left(\mathrm{X}_{\mathrm{C}}-\mathrm{X}_{\mathrm{L}}\right)^{2}}$
At resonance, X_C = X_L
So, Z is minimum.

Alternating Current MCQ Class 12 Question 14.

The power factor of series LCR circuit at resonance is –

(A) 0.707
(B) 1
(C) 0.5
(D) 0
Answer:
(B) 1

Explanation:
At resonance, LCR circuit behaves I as purely resistive circuit. For purely resistive circuit, power factor is 1.

Alternating Current MCQs Chapter 7 Question 15.

When a capacitor C is charged to a certain potential and connected to an inductor L, then frequency of energy oscillation is given by –

(A) Q = $\frac{1}{2 \pi \sqrt{L C}}$
(B) Q = $\frac{1}{\sqrt{\mathrm{LC}}}$
(C) Q = $\frac{2 \pi}{\sqrt{\mathrm{LC}}}$
(D) Q = $\frac{1}{2 \pi} \sqrt{\frac{L}{C}}$
Answer:
(A) Q = $\frac{1}{2 \pi \sqrt{L C}}$

Explanation:
When a capacitor C is charged to a certain potential and connected to an inductor L, energy stored in C oscillates between L and C.
X_L = X_C
∴ f = $\frac{1}{2 \pi \sqrt{\mathrm{LC}}}$

Alternating Current Class 12 MCQ Questions Question 16.

The output of a step-down transformer is measured to be 24 V when connected to a 12 W Light bulb. The value of the peak current is

(A) 1/$\sqrt{2}$ A
(B) $\sqrt{2}$ A
(C) 2 A
(D) 2$\sqrt{2}$ A
Answer:
(A) 1/$\sqrt{2}$ A

Explanation:

Power associated with secondary P_s = 12 W
Secondary voltage, V_s = 24 V
Current in the secondary, I_s = $\frac{P_{s}}{V_{s}}=\frac{12}{24}$ = 0.5 A
Peak value of the current in the secondary,
l₀ = I_s$\sqrt{2}$ = (0.5)(1.414)= 0.707 or $\frac{1}{\sqrt{2}}$ A

Class 12 Alternating Current MCQ Question 17.

The underlying principle of transformer is –

(A) resonance.
(B) mutual induction.
(C) self induction.
(D) none of the above.
Answer:
(B) mutual induction.

Explanation:
The transformer is based on the principle of mutual induction which state that due to continuous change in current in the primary coil, an emf is induced across the secondary soil.

Physics Chapter 7 MCQ Class 12 Question 18.

The core of a transformer is laminated as

(A) it improves the ratio of voltage in the primary and secondary may be increased.
(B) it checks rusting of the core may be stopped.
(C) it reduces energy losses due to eddy currents.
(D) it increases flux linkage.
Answer:
(C) it reduces energy losses due to eddy currents.

Explanation:
Laminated core means a layered core instead of a single solid core. Eddy currents are current loops generated by changing magnetic fields. They flow in a plane perpendicular to the magnetic field. Laminated magnetic core reduces eddy currents. For this reason, electrically isolated laminations are utilized to manufacture transformers.

Chapter 7 MCQ Class 12 Physics Question 19.

If rotational velocity of an armature is doubled, emf generated in a generator will be

(A) half.
(B) two times.
(C) four times.
(D) unchanged.
Answer:
(B) two times.

Explanation:
emf generated = NBA

Class 12 Physics Chapter 7 MCQ Questions Question 20.

Quantity that remains unchanged in a transformer is –

(A) voltage.
(B) current.
(C) frequency.
(D) none of these.
Answer:
(C) frequency.

Explanation:
Transformer does not change the frequency of the applied AC.

Alternating Current Class 12 MCQs Chapter 7 Question 21.

…………… increases in step-down transformer.

(A) Voltage
(B) Current
(C) Power
(D) Current density
Answer:
(B) Current

Explanation:
Since V_p/V_s = I_s/I_p, so as as voltage reduces, the current increases in a step-down transformer.

Question 22.

The efficiency of transformer is very high because

(A) There is no moving part
(B) It uses AC only
(C) It uses the copper wire for the coils
(D) None of the above
Answer:
(A) There is no moving part

Explanation:
Transformer is a static device which transforms power from one circuit to other through electromagnetic induction. In electrical transformer as there are no moving parts, no friction. Losses in the transformer are very less compared to any other rotating machine, hence efficiency of transformers will be very high which is about 95% to 98%.

Assertion And Reason Based MCQs (1 Mark each)

Directions: In the following questions, A statement of Assertion (A) is followed by a statement of Reason (R). Mark the correct choice as.
(A) Both A and R are true and R is the correct explanation of A
(B) Both A and R are true but R is NOT the correct explanation of A
(C) A is true but R is false
(D) A is false and R is true

Question 1.

Assertion (A): An alternating current does not show any magnetic effect.
Reason (R): Alternating current changes direction with time.

Answer:
(D) A is false and R is true

Explanation:
Current or moving charged particle creates magnetic field irrespective of direct current or alternating current. So assertion is false. Alternating current changes direction with time. So, the reason is true, but cannot explain the assertion.

Question 2.

Assertion (A): Capacitor blocks dc and allows ac to pass.
Reason (R): Capacitive reactance is inversely proportional to frequency.

Answer:
(A) Both A and R are true and R is the correct explanation of A

Explanation:
Capacitive reactance = $\frac{1}{2 \pi f C}$
So, as f (frequency) increases, reactance decreases.
For dc, frequency = 0, hence capacitor offers infinite reactance. So, it blocks dc.
For ac, frequency ≠ 0, hence capacitor offers low reactance and allows ac to pass.
Hence assertion and reason both are true. Assertion is properly explained by reason.

Question 3.

Assertion (A): V_RMSvalue of an alternating voltage V = 4$\sqrt{2}$ sin 314t is 4 volt.
Reason (R): Peak value of the alternating voltage is 442 volt.

Answer:
(B) Both A and R are true but R is NOT the correct explanation of A

Explanation:
Given alternating voltage
V = 4₀$\sqrt{2}$ sin 314t.
Where peak value = V₀/$\sqrt{2}$ = 4 volt.
V_RMS = V₀/$\sqrt{2}$ = 4 volt.
Hence both assertion and reason both are true. But the reason does not properly explain the assertion.

Question 4.

Assertion (A): Both ac and dc can be measured by hot wire instrument.
Reason (R): Hot wire instrument is based on the principal of magnetic effect of current.

Answer:
(C) A is true but R is false

Explanation:
In both ac and dc, heat generated is proportional to the square of current. Polarity change of ac is immaterial in the case of heat generation. Hence they can be measured by hot wire instrument. Hence, the assertion is true. Hot wire instruments are based on the principle of heating effect of current. Hence the reason is false.

Question 5.

Assertion (A): The dimension of L/R is time.
Reason (R): Time constant (L/R) should be increased to reduce the rate of increase of current through a solenoid.

Answer:
(B) Both A and R are true but R is NOT the correct explanation of A

Explanation:
For a solenoid, the magnitude of induced emf
e = L$\frac{d i}{d t}$
i = $\frac{e}{R}=\left(\frac{L}{R}\right)\left(\frac{d i}{d t}\right)$
$\frac{d i}{d t}=\frac{i}{\frac{L}{R}}$

In left hand side of the above equation, denominator is time. So, in right hand side, the denominator should be time. So, dimension of L/R is time. So, the assertion is true. If L/R increases, di/dt decreases. So, reason is also true. But reason cannot properly explain the assertion.

Question 6.

Assertion (A): At resonance, the current becomes minimum in a series LCR circuit.
Reason (R): At resonance, voltage and current are out of phase in a series LCR circuit.

Answer:
(D) A is false and R is true

Explanation:
At resonance, X_L = X_C, so the circuit impedance becomes minimum and resistive and hence the current becomes maximum. So, the assertion is false. At resonance, X_L = X_C so the circuit impedance becomes resistive. In resistive circuit voltage and current are always in same phase. Hence, reason is also false.

Question 7.

Assertion (A): When capacitive reactance is less than the inductive reactance in a series LCR circuit, e.m.f. leads the current.
Reason (R): The angle by which alternating voltage leads the alternating current in series RLC circuit is
given by tan φ = $\frac{X_{L}-X_{C}}{R}$

Answer:
(A) Both A and R are true and R is the correct explanation of A

Explanation:
The angle by which alternating voltage leads the alternating current in series RLC circuit is given by tan φ = $\frac{X_{L}-X_{C}}{R}$
If X_C < X_Lthen tan φ is positive, φ is also positive. So, e.m.f. leads the current. Assertion and reason both are true. Reason properly explains the assertion.

Question 8.

Assertion (A): Quality factor of a series LCR circuit is Q = $\frac{1}{R} \sqrt{\frac{L}{C}}$
Reason (R): As bandwidth decreases, Q increases in a resonant LCR circuit.

Answer:
(B) Both A and R are true but R is NOT the correct explanation of A

Explanation:
Quality factor of a series LCR circuit is Q = $\frac{1}{R} \sqrt{\frac{L}{C}}$ Assertion is true. Quality factor is also defined as

So, reason is also true. But reason does not explain the assertion.

Question 9.

Assertion (A): Principle of operation of AC generator is electromagnetic induction.
Reason (R): Resistance offered by inductor for AC is zero.

Answer:
(B) Both A and R are true but R is NOT the correct explanation of A

Explanation:
Principle of operation of AC generator is electromagnetic induction. The assertion is true.
Resistance offered by inductor = 2πfL. For AC, f ≠ 0. So, 2nfL ≠ 0. So, the reason is false.

Question 10.

Assertion (A): An alternator is a machine which converts mechanical energy into electrical energy.
Reason (R): When a coil rotates in a magnetic field an e.m.f. is induced in it.

Answer:
(A) Both A and R are true and R is the correct explanation of A

Explanation:
Alternator is basically a generator in which a coil rotates in a strong magnetic field and according to laws of electromagnetic induction e.m.f. is generated. So, assertion and reason both are true and reason explains the assertion.

Question 11.

Assertion (A): A transformer does not work on DC.
Reason (R): DC neither change direction nor magnitude.

Answer:
(A) Both A and R are true and R is the correct explanation of A

Explanation:
Transformer has two coils. If current fluctuates in one coil, e.m.f. is induced in the other coil. For DC supply current does not change, so there is no induced e.m.f. Hence both assertion and reason are true and reason explains the assertion.

Question 12.

Assertion (A): A step-up transformer converts input low AC voltage to output high AC voltage.
Reason (R): It violate the law of conservation of energy.

Answer:
(C) A is true but R is false

Explanation:
Step-up transformer means it converts input low AC voltage to output high AC voltage. So, the assertion is true.
For step up transformer, V_OUT/ V_IN >1, but simultaneously I_OUT /I_IN < 1 and P_IN = P_OUT (ideally). Hence, the law of conservation of energy is not violated.

Case-Based MCQs

Attempt any 4 sub-parts out of 5. Each sub-part carries 1 mark.

I. Read the following text and answer the following questions on the basis of the same:

Tuning a radio set:
In essence the simplest tuned radio frequency receiver is a simple crystal set. Desired frequency is tuned by a tuned coil / capacitor combination, and then the signal is presented to a simple crystal or diode detector where the amplitude modulated signal, is demodulated. This is then passed straight to the headphones or speaker. In radio set there is an LC oscillator comprising of a variable capacitor (or sometimes a variable coupling coil), with a knob on the front panel to tune the receiver.

Capacitor used in old radio sets is gang capacitor. It consists of two sets of parallel circular plates one of which can rotate manually by means of a knob. The rotation causes overlapping areas of plates to change, thus changing its capacitance. Air gap between plates acts as dielectric. The capacitor has to be tuned in tandem corresponding to the frequency of a station so that the LC combination of the radio set resonates at the frequency of the desired station.

Class 12 Physics Chapter 7 MCQ

When capacitive reactance (X_C) is equal to the inductive reactance (X_L), then the resonance occurs and the resonant frequency is given by ω₀ = $\frac{1}{\sqrt{L C}}$ current amplitude becomes maximum at the resonant frequency. It is important to note that resonance phenomenon is exhibited by a circuit only if both L and C are present in the circuit. Only then do the voltages across L and C cancel each other (both being out of phase) and the $\frac{V_{m}}{R}$ Current amplitude is the total source voltage appearing across R. This means that we cannot have resonance in a RL or RC circuit.

Question 1.

Name the phenomenon involved in tuning a radio set to a particular radio station.

(A) Stabilization
(B) Rectification
(C) Resonance
(D) Reflection
Answer:
(C) Resonance

Explanation:
Phenomenon involved in tuning a radio set to a particular radio station is resonance. The capacitor has to be tuned in tandem corresponding to the frequency of a station. So, that the LC combination of the radio set resonates at the frequency of the desired station.

Question 2.

Resonance may occur in:

(A) RL circuit.
(B) RC circuit.
(C) LC circuit.
(D) circuit having resistor only.
Answer:
(C) LC circuit.

Explanation:
A simple radio receiver is a simple crystal set with a coil and capacitor combination. Desired frequency is tuned by tuning the coil – capacitor combination. Tuning means to make capacitive reactance (X_C) equal to the inductive reactance (X_L), so that the resonance occurs.

Question 3.

Resonance frequency is equal to:

(A) $\frac{1}{\mathrm{LC}}$
(B) $1 / \sqrt{\mathrm{LC}}$
(C) $\sqrt{\frac{L}{C}}$
(D) $\sqrt{\frac{C}{L}}$

Answer:
(B) $1 / \sqrt{\mathrm{LC}}$

Explanation:
The resonant frequency is given by CQ0 = 1/VLC

Question 4.

Resonance occurs only when:

(A) X_C = R
(B) X_L = R
(C) X_L = X_C
(D) X_C>X_L
Answer:
(C) X_L = X_C

Explanation:
At resonance, capacitive reactance (X_C) is equal to the inductive reactance (X_L). Circuit is totally resistive and the current amplitude becomes maximum.

Question 5.

Capacitor used in radio set for tuning is a:

(A) parallel plate capacitor.
(B) spherical capacitor.
(C) paper capacitor.
(D) electrolytic capacitor.
Answer:
(A) parallel plate capacitor.

Explanation:
Capacitor used in old radio is a parallel plate capacitor. It consists of two sets of parallel circular plates, one of which can rotate manually by means of a knob. The rotation causes overlapping areas of plates to change, thus changing its capacitance.

II. Read the following text and answer the following questions on the basis of the same:
At power plant, a transformer increases the voltage of generated power by thousands of volts so that it can be sent of long distances through high-voltage transmission power lines. Transmission lines are bundles of wires that carry electric power from power plants to distant substations.
At substations, transformers lower the voltage of incoming power to make it acceptable for high- volume delivery to nearby end-users.
Electricity is sent at extremely high voltage because it Emits so-called line losses. Very good conductors of electricity also offer some resistance and this resistance becomes considerable over long distances causing considerable loss.
Chapter 7 Physics Class 12 MCQ

At generating station, normally voltage is stepped up to around thousands of volts. Power losses increase with the square of current. Therefore, keeping voltage high current becomes low and the loss is minimized. Another option of minimizing loss is the use of wires of super-conducting material. Super-conducting materials are capable of conducting without resistance, they must be kept extremely cold, nearly absolute zero, and this requirement makes standard super-conducting materials impractical to use.

However, recent advances in super-conducting materials have decreased cooling requirement. In Germany recently 1 km super-conducting cable have been installed connecting the generating station and the destination. It has eliminated the line loss and the cable is capable of sending five times more electricity than conventional cable. Using super-conducting cables Germany has also get rid of the need of costly transformers. Transformers generate waste heat when they are in operation and oil is the coolant of choice.

It transfers the heat through convection to the transformer housing, which has cooling fins or radiators similar to heat exchangers on the outside. Flush point is a very important parameter of transformer oil. Flashpoint of an oil is the temperature at which the oil ignites spontaneously. This must be as high as possible (not less than 160° C from the point of safety). Fire point is the temperature at which the oil flashes and continuously burns. This must be very high for the chosen oil (not less than 200° C).

Question 1.

Which of the following statement is true for long distance transmission of electricity?

(A) Step-down transformer is used at generating station and step-up transformer is used at destination substation.
(B) Step-down transformers are used at generating station and destination substation.
(C) Step-up transformers are used at generating station and destination substation.
(D) None of the above
Answer:
(D) None of the above

Explanation:
At power plant, a step-up transformer increases the voltage of generated power by thousands of volts, so that it can be sent of long distances through high-voltage transmission power lines. At substations, step-down transformers lower the voltage of incoming power to make it acceptable for high-volume delivery to nearby end-users.

Question 2.

Super-conducting transmission line has the following advantages:

(A) Resistance being zero, there is no I2,R loss.
(B) There is no requirement of costly step-up and step-down transformers.
(C) Cable is capable of sending more electricity.
(D) All of the above
Answer:
(D) All of the above

Explanation:
Super-conducting materials are capable of conducting without resistance. So, this eliminates the line loss and the cable is capable of sending more electricity than conventional cable. Using super-conducting cables, one can get rid of the need of costly transformers.

Question 3.

Why does stepping up voltages reduce power loss?

(A) Since resistance of conductor decreases with increase of voltage
(B) Since current decreases with increase of voltage
(C) Both of the above
(D) None of the above
Answer:
(B) Since current decreases with increase of voltage

Explanation:
At generating station, normally voltage is stepped up to around thousands of volts. Power losses increase with the square of current. Therefore, keeping voltage high, current becomes low and the loss is minimized.

Question 4.

Oil transfers heat from transformer winding by the process of:

(A) convection.
(B) conduction.
(C) radiation.
(D) All of these
Answer:
(A) convection.

Explanation:
Transformers generate waste heat when they are in operation and oil is the coolant of choice. It transfers the heat through convection to the transformer housing.

Question 5.

Flush point of an oil is –

(A) the temperature at which the oil flashes and continuously burns.
(B) the temperature at which the oil ignites spontaneously.
(C) the temperature at which the oil starts boiling.
(D) The temperature at which the oil forms fumes.
Answer:
(B) the temperature at which the oil ignites spontaneously.

Explanation:
Flush point is a very important parameter of transformer oil. Flashpoint of an oil is the temperature at which the oil ignites spontaneously. This must be as high as possible (not less than 160° C from the point of safety).

III. Read the following text and answer the following questions on the basis of the same:

Losses of transformer:
There are 4 types of losses in a transformer: Core loss, Ohmic loss, Stray load loss and dielectric loss.

(1) Core loss :
Core loss has two components – hysteresis loss and eddy current loss. These together are called no-load losses of a transformer and are calculated by open circuit test.
(a) Hysteresis loss: This loss mainly depends on the core material used in the transformer. To reduce this loss, the high-grade core material can be used. CRGO- Cold rolled grain oriented Si steel is commonly used for this purpose.
(b) Eddy current loss: This loss can be reduced by designing the core using slight laminations.
These losses are present even when no load is connected. So, these are also known as no-load loss.

(2) Copper Loss:
Copper losses occur because of the Ohmic resistance in the windings of the transformer. If the currents in primary and secondary windings of the transformer are I₁ and I₂, and if the resistances of these windings are R₁ & R₂ then the copper losses that occurred in the windings are I₁²R₁ & I₂²R₂² respectively. So, the entire copper loss will be I₁²R₁ + I₂²R₂ This loss is also called variable or ohmic losses because this loss changes based on the load.

(3) Stray Loss :
These types of losses in a transformer occur because of the occurrence of the leakage flux. As compared with copper and iron losses, the percentage of stray losses are less, so these losses can be neglected.

(4) Dielectric Loss :
This loss mainly occurs within the oil of the transformer. Oil is an insulating material. Once the oil quality in the transformer deteriorates then the transformer’s efficiency is affected. Efficiency of Transformer It is the ratio of output power and input power. Efficiency = Output Power / Input Power. The transformer is a highly efficient device which ranges between 95% – 98.5%.

Question 1.

What is the relationship among core loss, hysteresis loss and eddy current loss?

(A) Eddy current loss = Core loss + Hysteresis loss
(B) Core loss = Hysteresis loss + eddy current loss
(C) Hysteresis loss = Core loss + eddy current loss
(D) Core loss = Hysteresis loss X eddy current loss
Answer:
(B) Core loss = Hysteresis loss + eddy current loss

Question 2.

Which of the following losses in transformer is also known as no-load loss?

(A) Copper loss
(B) Stray loss
(C) Dielectric loss
(D) Core loss
Answer:
(D) Core loss

Explanation:
Core loss is present even when no load is connected. So, these are also known as no-load loss.

Question3.

Which of the following losses in transformer is also known as variable loss?

(A) Copper loss
(B) Stray loss
(C) Dielectric loss
(D) Core loss
Answer:
(A) Copper loss

Explanation:
If the currents in primary and secondary windings of the transformer are I₁ and I₂ respectively and the resistances of these windings are R₁ and R₂ then the copper losses that occurred in the windings are I₁²R₁ and I₂²R₂ respectively. So, the entire copper loss will be I₁²R₁ + I₂²R₂. This loss is also called variable or ohmic losses because this loss changes based on the load.

Question 4.

How hysteresis loss can be reduced?

(A) Using core of Si Steel
(B) Using laminated core
(C) Using core of non-ferro magnetic material
(D) Using oil of higher dielectric constant
Answer:
(A) Using core of Si Steel

Question 5.

Specify the range of transformer efficiency.

(A) 10 – 15%
(B) 95 – 98%
(C) 50 – 60%
(d) 40 – 50%
Answer:
(B) 95 – 98%

MCQ Questions for Class 12 Physics with Answers

MCQ Questions for Class 12 Biology Chapter 3 Human Reproduction

January 24, 2023January 22, 2023 by Prasanna

Human Reproduction Class 12 MCQ Questions With Answers

Human Reproduction Class 12 MCQ Chapter 3 Question 1.

Spot the odd one out from the following structures with reference to the male reproductive system.

(A) Rete testis
(B) Epididymis
(C) Vasa efferentia
(D) Isthmus
Answer:
(D) Isthmus

Explanation :
Rete testis, vasa efferentia and epididymis are parts of male reproductive system whereas isthmus is part of fallopian tube which carries an egg from the ovary to the uterus.

Class 12 Biology Chapter 3 MCQ Question 2.

Which one of the following is not a male accessory gland?

(A) Seminal vesicle
(B) Ampulla
(C) Prostate
(D) Bulbo-urethral gland
Answer:
(B) Ampulla

Chapter 3 Biology Class 12 MCQ Question 3.

The vas deferens receives duct from the seminal vesicle and opens into urethra as

(A) epididymis
(B) ejaculatory duct
(C) efferent ductule
(D) ureter
Answer:
(B) ejaculatory duct

Explanation :
The vas deferens receives duct from the seminal vesicle and opens into urethra as ejaculatory duct. These ejaculatory . ducts which open into the urethra about hnlf way through the prostate gland function to mix Lhc sperm stored in the ampulla with fluids secreted by the seminal vesicles and to transport these substances to the prostate.

Human Reproduction Class 12 MCQ With Answers Question 4.

Urethral meatus refers to the

(A) urinogenital duct.
(B) opening of vas deferens into urethra.
(C) external opening of the urinogenital duct.
(D) muscles surrounding the urinogenital duct.
Answer:
(C) external opening of the urinogenital duct.

Explanation :
Urethral meatus, also known as the external urethral orifice, is the external opening or meatus of the urethra. The urethra originates from the urinary bladder and ex tends through the penis to its external opening called urethral meatus.

MCQ On Human Reproduction Class 12 Pdf Question 5.

Seminal plasma, the fluid part of semen, is on tributed by

(i) Seminal vesicle
(ii) Prostate
(iii) Urethra
(iv) Bulbo-urethral gland

(A) i and ii
(B) i, ii and iv
(C) ii, iii and iv
(D) i and iv
Answer:
(B) i, ii and iv

Explanation :
Secretion of seminal vesicle (paired), prostate gland (unpaired) and bulbo-urethral glands or Cowper’s glands (paired) constitute the seminal plasma. It contains various proteins and fructose as energy suppliers for sperm motility and is also responsible for making the largest proportion of the alkaline buffer.

Biology Class 12 Chapter 3 MCQs Question 6.

Identify the odd one from the following.

(A) Labia minora
(B) Fimbriae
(C) Infundibulum
(D) Isthmus
Answer:
(A) Labia minora

Explanatio:
Fimbriae, infundibulum, isthmus I and ampulla are the parts of fallopian duct I while labia minora is female external genitalia.

Chapter 3 Biology Class 12 MCQs Question 7.

Prostate glands are located below

(A) gubernaculum
(B) seminal vesicles
(C) epididymis
(D) bulbourethral glands
Answer:
(B) seminal vesicles

Explanation:
Prostate gland is the part of male reproductive system that is located just be¬low the bladder. Small and walnut shaped, the prostate surrounds the beginning of the urethra.

Class 12 Biology Ch 3 MCQ Question 8.

Lower narrow end of uterus is called

(A) urethra
(B) cervix
(C) clitoris
(D) vulva
Answer:
(B) cervix

Explanation :
Lower end of uterus is called cervix that opens into vagina. A hollow muscular organ located in front of the rectum and behind the urinary bladder, at the lower end of uterus is called cervix that opens into vagina.

MCQ Class 12 Biology Chapter 3 Question 9.

The third stage of parturition is called “after-birth”. In this stage

(A) excessive bleeding occurs
(B) fetus is born and cervix and vagina contraction to normal condition happens
(C) fetus is born and contraction of uterine wall prevents excessive bleeding
(D) placenta is expelled out.
Answer:
(D) placenta is expelled out.

Explanation:
Third process of parturition is the third and final stage, after the delivery until the placenta or after birth is expelled by powerful uterine contractions. Umbilical cord is cut close to the baby’s navel. It lasts for 10-15 minutes after the birth of child.

Human Reproduction MCQ Chapter 3 Question 10.

Which of the following contains the actual genetic part of a sperm?

(A) Whole of it
(B) Tail
(C) Middle piece
(D) Head
Answer:
(D) Head

Explanation :
Head of the sperm is anterior, broad, flattened and almond shape. It consists of two parts. The head portion is mainly a cell nucleus; it consists of genetic substances and anterior small cap-like acrosome. The nucleus consists of condensed DNA and basic proteins.

MCQs Of Biology Class 12 Chapter 3 Question 11.

Identify the wrong statement from the following.

(A) High levels of oestrogen trigger the ovulatory surge.
(B) Oogonial cells start to proliferate and give rise to functional ova in regular cycles from puberty onwards.
(C) Sperms released from seminiferous tubules are poorly motile/non-motile.
(D) Progesterone level is high during the post-ovulatory phase of menstrual cycle.
Answer:
(B) Oogonial cells start to proliferate and give rise to functional ova in regular cycles from puberty onwards.

Explanation :
Oogenesis is initiated during the embryonic developmental stage when a couple of million gamete mother cell (oogonia) is formed within each foetal ovary (about third month of foetal ovary). Unlike sperm forma¬tion that starts at puberty egg formation begins before birth. No more oogonia are formed and added after birth.

MCQ Questions For Class 12 Biology Chapter 3 Question 12.

The immature male germ cells undergo division to produce sperms by the process of spermatogenesis. Choose the correct one with reference to above.

(A) Spermatogonia have 46 chromosomes and always undergo meiotic cell division.
(B) Primary spermatocytes divide by mitotic cell division.
(C) Secondary spermatocytes have 23 chromosomes and undergo second meiotic division.
(D) Spermatozoa are transformed into spermatids.
Answer:
(C) Secondary spermatocytes have 23 chromosomes and undergo second meiotic division.
Explanation:
Spermatogonia have 46 chromosomes and always undergo mitotic cell division. Primary spermatocytes divide by meiotic cell division. Spermatids are transformed into spermatozoa.

Class 12th Biology Chapter 3 MCQ Question 13.

Spermiation is the process of the release of sperms from

(A) seminiferous tubules.
(B) vas deferens.
(C) epididymis.
(D) prostate gland.

Explanation:
Spermiation is the process by which mature spermatids or spermatozoa are released from Sertoli cells into the seminiferous tubule lumen prior to their passage to the epididymis.

MCQ Of Human Reproduction Class 12 Question 14.

Match between the following representing parts of the sperm and their functions and choose the correct option.

Column A	Column B
A. Head	i. Enzymes
B. Middle piece	ii. Sperm motility
C. Acrosome	iii. Energy
D. Tail	iv. Genetic material

(A) A-ii, B-iv, C-i, D-iii
(B) A-iv, B-iii, C-i, D-
(C) A-iv, B-i, C-ii, D-iii
(D) A-ii, B-i, C-iii D-iv
Answer:
(B) A-iv, B-iii, C-i, D-

Explanation:
A. Sperm head contains nucleus with densely coiled chromatin fibers surrounded by acrosome. Nucleus transfers the genetic material to next generation.

B. Middle piece of sperm contains large number of mitochondria to provide energy needed for the movement.

C. Acrosome present in the cap of sperm contains hydrolytic enzymes which help sperm to penetrate the egg. These enzymes break down the outer membrane of the ovum, called the zona pellucida, allowing the haploid nucleus in the sperm cell to join with the haploid nucleus in the ovum.

D. Tail of sperm helps in propelling or swimming the sperm cell forwards to meet the egg.

MCQ On Human Reproduction Class 12 Question 15.

Mature Graafian follicle is generally present in the ovary of a healthy human female around stet.

(A) 5-8 days of menstrual cycle.
(B) 11-17 days of menstrual cycle.
(C) 18-23 days of menstrual cycle.
(D) 24-28 days of menstrual cycle.
Answer:
(B) 11-17 days of menstrual cycle.

Explanation:
Mature Graafian follicle is the fol¬licular stage present in the ovary. It is formed after the completion of first mitotic division but before ovulation. It, therefore, contains a 2N diploid oocyte. Graafian follicle is characterized by a large follicular antrum and releases one or more ova into the Fallopian tube and leaves behind the corpus luteum. It is generally present in the ovary of a healthy human female around 11-17 days of menstrual cycle.

Class 12 Human Reproduction MCQ Chapter 3 Question 16.

Which among the following has 23 chromosomes?

(A) Spermatogonia
(B) Zygote
(C) Secondary oocyte
(D) Oogonia
Answer:
(B) Zygote

Explanation :
Secondary oocyte (n = 23). Primary oocyte completes first meiotic division to form secondary oocyte (23 chromosomes) and polar body (23 chromosomes), whereas spermatogonia, zygote and oogonia have 46 chromosomes, hence diploid.

MCQs On Human Reproduction Class 12 Question 17.

The membranous cover of the ovum at ovulation is

(A) corona radiata.
(B) zona radiata.
(C) zona pellucida.
(D) chorion.
Answer:
(A) corona radiata.

Explanation :
Corona radiata is the innermost layer of the cells of the cumulus oophorus and is directly adjacent to the zona pellucida, the outer protective glycoprotein layer of the ovum. Zona radiata is a striated membrane situated next the yolk of an ovum. Chorion is an extra-embryonic fetal membrane which is responsible for the formation of placenta.

Chapter 3 Class 12 Biology MCQ Question 18.

At what stage of life is oogenesis initiated in a human female?

(A) At puberty
(B) During menarch
(C) During menopause
(D) During embryonic development
Answer:
(D) During embryonic development

Explanation :
During embryonic development, the process of formation of haploid ova from diploid germinal cell is called oogenesis and the process occurred in the ovary. Oogenesis begins during embryonic development but is completed only at puberty of the secondary oocyte with the sperm.

Biology Class 12 Chapter 3 MCQ Question 19.

A human female reaches menopause around the age of

(A) 50 years
(B) 15 years
(C) 70 years
(D) 25 years.
Answer:
(A) 50 years

Explanation :
The end of a woman’s fertility is called menopause and the stop of the menstrual cycle. The ovaries stop producing hormones and in humans, the menstrual cycle ceases at around 50 years of age. but sometimes due to health-related problems it varies.

Class 12 Biology Chapter 3 MCQs Biology Question 20.

Layers of an ovum from outside to inside is

(A) corona radiata, zona pellucida and vitelline membrane
(B) zona pellucida, corona radiata and vitelline membrane
(C) vitelline membrane, zona pellucida and corona radiata
(D) zona pellucida, vitelline membrane and corona radiata.

Explanation :
The corona radiata is thick and the outer layer of follicular (granulosa), zona pellucida is inner and thick and non cellular. The zona pellucida surrounds the oocyte and located between the oocyte and the follicular cells. The vitelline membrane is a membrane enclosing an egg that comprises the zona pellucida in mammals.

MCQ Of Chapter 3 Biology Class 12 Question 21.

Choose the incorrect statement from the following.

(A) In birds and mammals internal fertilization takes place.
(B) Colostrum contains antibodies and nutrients.
(C) Polyspermy is prevented by the chemical changes in the egg surface.
(D) In the human female implantation occurs almost seven days after fertilization.
Answer:
(C) Polyspermy is prevented by the chemical changes in the egg surface.

Explanation :
Polyspermy may be defined as the fertilization of an ovum by more than one sperm. During fertilization, a sperm comes in contact with the zona pellucida layer of the ovum and induces changes in the membrane that block the entry of additional sperms. Thus, it ensures that only one sperm can fertilize an ovum.

Question 22.

Acrosomal reaction of the sperm occurs due to

(A) its contact with zona pellucida of the ova.
(B) reactions within the uterine environment of the female.
(C) reactions within the epididymal environment of the male.
(D) androgens produced in the uterus.
Answer:
(A) its contact with zona pellucida of the ova.

Explanation :
Acrosomal reaction of the sperm occurs due to its contact with zona pellucida of the ova. The reaction that occurs in acrosome of sperm is triggered by the release of fertilizin. The main purpose of the acrosomal reaction is to start the fusion of the oocyte membrane with the sperm cell membrane allowing the combination of genetic material contained in both gametes, leading to the fertilization of the oocyte.

Question 23.

Morula is a developmental stage

(A) between the zygote and blastocyst.
(B) between the blastocyst and gastrula.
(C) after the implantation.
(D) between implantation and parturition.
Answer:
(A) between the zygote and blastocyst.

Explanation :
Morula is a developmental stage between the zygote and blastocyst. It is a solid ball of 16-32 blastomeres, produced by a series of cleavage divisions of the early embryo from which a blastula is formed.

Question 24.

Match the following and choose the correct options.

Column I	Column II
A. Trophoblast	i. Embedding of blastoyst in the endometrium
B. Cleavage	ii. Group of cells that would differentiate as embryo
C. Inner cell mass	iii. Outer layer of blastocyst attached to the endometrium
D. Implantation	iv. Mitotic division of zygote

(A) A-ii, B-i, C-iii, D-iv
(B) A-iii, B-iv, C-ii, D-i
(C) A-iii, B-i, C-ii, D-iv
(D) A-ii, B-iv, C-iii, D-i
Answer:
(D) A-ii, B-iv, C-iii, D-i

Explanation:
A. Trophoblast is the peripheral cells of the blastocyst, which attach the zygote (fertilised ovum) to the uterine wall and become the placenta and the membranes that nour¬ish and protect the developing organism.
B. Cleavage is the repeated mitotic division of cells in the early embryo.
C. Inner cell mass forms within the blastocyst, prior to its implantation within the uterus.
It differentiates to form embryo.
D. Implantation is a process of attachment and invasion of the uterus endometrium by the blastocyst (conceptus).

Question 25.

Which of the following hormones is not secreted by human placenta?

(A) hCG
(B) Estrogens
(C) Progesterone
(D) LH
Answer:
(D) LH

Explanation :
The major hormones secreted by the human placenta are : Human chorionic gonadotropin (hCG), estrogen, progesterone and human placental lactogen. LH (luteinising hormone) is produced by gonadotropic cells in the anterior pituitary gland. This hormone is considered a gonadotrophic hormone because of its role in controlling the function of ova¬ries in females and testes in. males, which are known as the gonads.

Question 26.

The early-stage human embryo distinctly possesses

(A) gills
(B) gill slits
(C) external ear (pinna)
(D) eyebrows.
Answer:
(B) gill slits

Explanation :
Early embryo, organism of vari¬ous vertebrates possesses a dorsal hollow nerve cord, a well developed notochord and a series of gill slits, which represent the fundamental chordate characters.

Question 27.

Gastrula is the embryonic stage in which

(A) cleavage occurs
(B) blastocoel form
(C) germinal layers form
(D) villiform.
Answer:
(C) germinal layers form

Explanation :
Transformation of the blastocyst into gastrula with primary germ layers by rearrangement of the cells is called gastrulation. During gastrulation, the embryo develops three germ layers (endoderm, mesoderm, and ectoderm) The structures derived from ectoderm are

(i) pituitary gland
(ii) cornea
(iii) kidneys
(iv) notochord

(A) (i) and (iii)
(B) (ii) and (iii)
(C) (i) and (ii)
(D) (ii) and (iv).
Answer:
(C) (i) and (ii)

Explanation:
Germ layer Derivatives
Ectoderm -Epidermis, neural tissue, hair, nails, enamel of teeth, etc.
Mesoderm – Blood vessel, joints, connective tissue, skeletal muscles, kidney, etc.
Endoderm – Epithelium of mouth, intestine, liver, etc.

Question 28.

Implantation takes place after fertilization.

(A) 5 days
(B) 6 days
(C) 7 days
(D) 8 days
Answer:
(C) 7 days

Explanation :
When a fertilized egg- travels down the fallopian tube and embedding of the blastocyst into endometrium of uterus is called implantation . Implantation begins about 7th day after fertilisation of ovum and it takes about 3 days for the process to be completed.

Question 29.

Cleavage differs from mitosis in lacking

(A) synthetic phase
(B) growth phase
(C) both (A) and (B)
(D) none of these.
Answer:
(B) growth phase

Explanation :
Cleavage starts after fertilization and it occurs in fallopian tube. It is holoblastic. There is no growth phase, so it differs from mitosis.

Question 30.

In human adult females oxytocin

(A) stimulates pituitary to secrete vasopressin
(B) causes strong uterine contractions during parturition
(C) is secreted by anterior pituitary
(D) stimulates growth of mammary glands.
Answer:
(B) causes strong uterine contractions during parturition

Explanation :
Oxytocin is produced in the hypothalamus and is secreted by the posterior pituitary gland. It causes contraction during parturition and help to bring baby out from the mother’s womb

Assertion and Reason Based MCQs

Directions: In the following questions a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as :

(A) Both assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of assertion (A).
(B) Both assertion (A) and Reason (R) are true but reason (R) is not the correct explanation of assertion (A).
(C) Assertion (A) is true but reason (R) is false.
(D) Assertion (A) is false but reason (R) is true.

Question 1.

Assertion (A): Urethra in human male act as a urinogenital canal.
Reason (R): Urethra carries only urine while sperms are carried by vasa deferentia only.

Answer:
(B) Both assertion (A) and Reason (R) are true but reason (R) is not the correct explanation of assertion (A).

Explanation :
Urethra is the canal through which both urine and semen is discharged therefore it is called urinogenital canal.

Question 2.

Assertion (A) : In human male, testes are extraabdominal and lie in scrotal sacs.
Reason (R): Scrotum protects the testes.

Answer:
(A) Both assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of assertion (A).

Explanation :
The scrotum is a bag-like struc¬ture that helps to protect the testicles. Testicles make sperm and for this, they need to be cooler than the inside of the body. This is why the scrotum is located outside the body.

Question 3.

Assertion (A): The region outside the seminiferous tubules is called interstitial spaces, which contain Leydig’s cells.
Reason (R): Leydig’s cells synthesize and secrete testicular hormones called androgen.

Answer:
(B) Both assertion (A) and Reason (R) are true but reason (R) is not the correct explanation of assertion (A).

Explanation :
Hypothalamus releases GnRH. This hormone stimulates the secretion of LH, which further acts on interstitial cells of Leydig and induces the release of androgen.

Question 4.

Assertion (A): Large members of mitochondria are present in middle piece of sperm.
Reason (R): Numerous mitochondria in the middle piece of sperm produce energy which is required for their movement.

Answer:
(A) Both assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of assertion (A).

Explanation :
Mitochondria is a powerhouse organelle. It stores energy in the form of ATE This energy helps in sperm motility.

Question 5.

Assertion (A): The secretory phase in the human menstrual cycle is also called the luteal phase.
Reason (R): During the luteal phase development of corpus luteum and secretion of progesterone occurs.

Answer:
(A) Both assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of assertion (A).

Explanation :
The luteal phase begins after ovulation. It lasts about 14 days and ends just before a menstrual period. In this, the ruptured follicle closes after releasing the egg and forms the corpus luteum.

Question 6.

Assertion (A): Vasa efferentia develop from rete testis.
Reason (R): Sperm conduction takes place by the ciliary current.

Answer:
(A) Both assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of assertion (A).

Explanation:
Vasa efferentia are short, straight tubes, develop from rete testis. They help in sperm conduction which takes place by the ciliary current.

Question 7.

Assertion (A): The fusion of sperm and ovum to form zygote is called fertilization.
Reason (R): It occurs at ampullary isthmic junction of the fallopian tube.

Answer:
(B) Both assertion (A) and Reason (R) are true but reason (R) is not the correct explanation of assertion (A).

Explanation :
Fertilization in humans occurs at I the ampullary isthmic junction of the fallopian tube. The fusion of sperm and ovum to form a zygote is called fertilization.

Question 8.

Assertion (A): Oxytocin helps in parturition.
Reason (R): Oxytocin acts on uterine muscle and causes expulsion of the fetus.

Answer:
(A) Both assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of assertion (A).

Explanation :
Oxytocin acts on uterine muscles and also increases the production of prostaglandins, which increase the contractions further.

Question 9.

Assertion (A): Endometrium is a mucosal tissue made up of two layers.
Reason (R): It is a inner lining of the uterus. Each month it thickens and renews itself, preparing for pregnancy.

Answer:
(A) Both assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of assertion (A).

Explanation :
It’s two layers-the strata fune rationalize and stratum basalis. If conception takes place, the embryo implants into the endometrium.

Question 10.

Assertion (A): The Leydig cells of testis are present outside the seminiferous tubules.
Reason (R): Testis helps to synthesize and secrete hormones called androgens.

Answer:
(A) Both assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of assertion (A).

Question 11.

Assertion: The gamete formed in males determines the sex of the offspring.
Reason: Sex determination in humans depends upon cumulative effect of some genes of X and Y chromosomes.

Answer:
(A) Both assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of assertion (A).

Explanation :
Sex determination depends either of the chromosomes contributed by male, If a chromosome is contributed in zygote formation the offspring will be male and if Y is contributed then the offspring will be female.

Case-Based MCQs

Attempt any 4 sub-parts from each question. Each sub-part carries 1 mark.

I. Read the following text and answer the following questions on the basis of the same:
During sexual reproduction, the male inserts the sperm into the female reproductive tract, and sperm receive by the ovary and after that sperm fuse with the egg (ovum) in the ampullary region, this process is called fertilization, haploid nucleus of sperm fuse with that of ovum to form Diploid zygote.

Question 1.

The phenomenon of sperm activation in mammals is known as.

(A) Parthenogenesis
(B) Amphimixis
(C) Capacitation
(D) Acrosomal reaction
Answer:
(C) Capacitation

Explanation:
This step is a biochemical event, in which the acrosome reaction occurs so, the reaction can penetrate the zona pellucida of the oocyte and fertilize with the egg (ovum).

Question 2.

Fertilization takes place in

(A) Vagina
(B) Follicle
(C) Uterus
(D) Fallopian tube
Answer:
(D) Fallopian tube

Explanation :
Fusion of sperm with an egg is known as fertilization, most of the time student’s think that this process occurs in ovary but that’s not true it actually occur In the fallopian tube that links an ovary to the uterus fertilized egg successfully travels down the fallopian tube and implants in the uterus.

Question 3.

Egg development without fertilization is known as

(A) Gametogenesis
(B) Parthenogenesis
(C) Metagenesis
(D) Oogenesis
Answer:
(B) Parthenogenesis

Explanation: Parthenogenesis is a method in which a new individual developed without fertilization, and there is no involvement of male gamete, e.g., Honey bee and drosophila, etc.

Question 4.

Site of fusion of sperm with an ovum.

(A) Infundibulum
(B) Ampullary isthmic junction of oviduct
(C) Cervix of uterus
(D) Ovary
Answer:
(B) Ampullary isthmic junction of oviduct

Explanation :
Fallopian tube has three parts first is isthmus second is ampulla (ampullary – isthmic junction) is the most common site for fertilization and the third is infundibulum which is farthest from the uterus, and the first cleavage division of zygote occurs in the ampullary-isthmic junction.

Directions: In the following questions a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as :

Question 5.

Assertion (A): All copulations do not lead to the fertilization and pregnancy.
Reason (R): Fertilisation can occur only if the ovum and sperms are transported simultaneously to the ampullary isthmic junction.

Answer:
(A) Both assertion (A) and Reason (R) are true and Reason (R) is the correct explanation of assertion (A).

II. Read the following text and answer the following questions on the basis of the same:

Read the passage and answer any four questions: Implantation is the embedding of the blastocyst into the endometrium of the uterus. Blastocyst is a ball of cells with a large, fluid-filled cavity called the blastocoel. The blastomeres in the blastocyst are arranged into an outer layer called trophoblast and inner cell mass. With the formation of blastocoel, morula is converted to blastula which is called blastocyst in mammals.

Question 1.

State of embryo development, in which implantation occurs in human female is :

(A) Morula
(B) Zygote
(C) Blastocyst
(D) Transient 3-celled stage.
Answer:
(C) Blastocyst

Explanation :
Blastocyst implant in the uterus, normally developing embryo will contain about six to 10 cells,

Question 2.

Which organ is formed during gastrulation?

(A) Gill
(B) Vitelline membrane
(C) Archenteron
(D) Heart.

Explanation :
The primary gut that forms: during gastrulation in the developing zygote is j known as the archenteron.

Question 3.

The process that transforms the embryo into a three-layered stage is called

(A) Blastulation
(B) Cleavage
(C) Gastrulation
(D) Organogenesis.
Answer:
(C) Gastrulation

Explanation :
The process that transforms the embryo into a three-layered stage is called gastrulation (a phase early in the embryonic de¬velopment of most animals).

Question 4.

The ectoderm cells will form the

(A) Skeletal system
(B) Nervous system
(C) Excretory system
(D) Respiratory system
Answer:
(B) Nervous system

Explanation :
Ectodermal cells form the central nervous system.

Directions: In the following questions a statement of assertion (A) is followed by a statement of reason (R). Mark the correct choice as :

Question 5.

Assertion (A): Blastocyst undergoes gastrulation to form three germinal layers.
Reason (R): This involves cell movements (morphogenetic movement) that help to attain new shape and morphology of embryo.

Answer:
(C) Assertion (A) is true but reason (R) is false.

Explanation :
During gastrulation, the blastula reorganizes cells migrate to the interior of the embryo, forming the three germ layers.

III. Study the given diagram and answer any of the four questions given below :
Human Reproduction Class 12 MCQ Chapter 3

Question 1.

Identify the parts labeled 1, 2, and 3 in the diagram given.

(A) 1-Placental villi, 2-Umbilical cord with its vessels, 3-Yolk sac.
(B) 1- Umbilical cord with its vessels, 2- Yolk sac, 3- Placental villi
(C) 1- Yolk sac, 2- Umbilical cord with its vessels, 3- Placental villi
(D) None of these
Answer:
(A) 1-Placental villi, 2-Umbilical cord with its vessels, 3-Yolk sac.

Explanation :
1. Placental villi having finger-like projections
2. the Umbilical cord is a tube that connects you to your baby during pregnancy.
3. The yolk sac is a membranous sac attached to an embryo.

Question 2.

During embryonic development which of the following is formed first?

(A) Heart
(B) Brain
(C) Skin
(D) Neural tube.
Answer:
(D) Neural tube.

Explanation :
During embryonic development Neural tube formed first, it is the embryonic precursor to the central nervous system.

Question 3.

The signals for parturition originate from :

(A) Placenta only
(B) Placenta as well as fully developed fetus
(C) Oxytocin released from maternal pituitary.
(D) Fully developed fetus only.
Answer:
(B) Placenta as well as fully developed fetus

Explanation :
The signals for parturition originate from Placenta as well as fully developed foetus, which prompt little uterine contraction is known as fetal expulsion reflex

Question 4.

Hormones secreted by the placenta to maintain pregnancy are:

(A) hCG, hPL, progesterone, prolactin
(B) hCG, progesterone, estrogen, glucocorticoid
(C) hCG, hPL, progesterone, estrogen
(D) hCG, hPL, estrogen, relaxin oxytocin.
Answer:
(C) hCG, hPL, progesterone, estrogen

Explanation :
hCG, progesterone, estrogens and human placental lactogen, are secreted by the placenta during pregnancy.

Question 5.

Gestation period in humans is :

(A) 10 weeks
(B) 28 weeks
(C) 32 weeks
(D) 38 weeks
Answer:
(D) 38 weeks

Explanation :
The average length of human gestation is 38 weeks, from the first day of the woman’s last menstrual period.

MCQ Questions for Class 12 Biology with Answers

Journey to the End of the Earth Class 12 MCQ Questions with Answers English Chapter 3

January 24, 2023January 22, 2023 by Prasanna

Check the below NCERT MCQ Questions for Class 12 English Vistas Chapter 3 Journey to the End of the Earth with Answers Pdf free download. MCQ Questions for Class 12 English with Answers were prepared based on the latest exam pattern. We have provided Journey to the End of the Earth Class 12 English MCQs Questions with Answers to help students understand the concept very well. You can also practice NCERT Solutions for Class 12 English on LearnInsta.com. https://mcqquestions.guru/journey-to-the-end-of-the-earth-class-12-mcq-questions/

MCQ Questions for Class 12 English Vistas Chapter 3 Journey to the End of the Earth with Answers

Journey to The End Of The Earth MCQ Class 12 Question 1.
How does visit to Antartica help to understand the effect of global warming?
(a) here one can see quickly melting glaciers and collapsing ice-shelves
(b) it is filled with snow
(c) it is away from urban rush
(d) it has hidden treasures.

Answer

Answer: (a) here one can see quickly melting glaciers and collapsing ice-shelves

MCQ Of Journey to The End Of The Earth Class 12 Question 2.
The geographical phenomena is going to help us to know the history of mankind_________
(a) by showing the global warming
(b) by showing the imapacts of global warming
(c) by telling the age of existence of human beings on the earth
(d) by exploring the world of ice

Answer

Answer: (c) by telling the age of existence of human beings on the earth

Journey to The End Of The Earth Class 12 MCQ Question 3.
Who is the author of the lesson Journey to the end of the Earth?
(a) Tishani Doshi
(b) Kamla Das
(c) Jane Austen
(d) Chitra Das

Answer

Answer: (a) Tishani Doshi

Journey to The End Of The Earth MCQs Class 12 Question 4.
What is the meaning of ‘epiphany’?
(a) a moment of shock
(b) a moment of great sadness
(c) cacophony
(d) a moment of sudden and great revelation or realization

Answer

Answer: (d) a moment of sudden and great revelation or realization

MCQ On Journey to The End Of The Earth Class 12 Question 5.
The name of the programme that takes high school students to the end of the earth is ________.
(a) Students of Ice
(b) Students for Ice
(c) Students above Ice
(d) Students on Ice

Answer

Answer: (d) Students on Ice

MCQ Journey to The End Of The Earth Class 12 Question 6.
What does the author mean by “In that short amount of time, we’ve managed to create quite a ruckus”?
(a) progress made by human race
(b) destruction and disturbance caused by human race
(c) stunning achievements of human race
(d) None of the above

Answer

Answer: (b) destruction and disturbance caused by human race

Journey to The End Of The Earth MCQ Questions Question 7.
The synonym of ‘ubiquitous’ is __________.
(a) abstract
(b) complex
(c) omnipresent
(d) simple

Answer

Answer: (c) omnipresent

MCQs Of Journey to The End Of The Earth Class 12 Question 8.
The Drake Passage was created because of _________.
(a) India drifting northwards
(b) South America drifting off to join North America
(c) North America drifting off to join South America
(d) India’s collision with Asia

Answer

Answer: (b) South America drifting off to join North America

Question 9.
Gondwana existed roughly around ___________.
(a)110 million years ago
(b)450 million years ago
(c)250 million years ago
(d) 650 million years ago

Answer

Answer: (d) 650 million years ago

Question 10.
The narrator was aboard on the ship named ______
(a) World carrier
(b) Academic Discovery
(c) Akademik Shokalskiy
(d) Denim Explorer

Answer

Answer: (c) Akademik Shokalskiy

Question 11.
What was the name of the Southern Super continent?
(a) Asia
(b) Asia Pacific
(c) Northern pole
(d) Gondwana

Answer

Answer: (d) Gondwana

Question 12.
What gives us an insight into the world’s geological history?
(a) Study of Northern Pole
(b) Study of Southern Pole
(c) Study of Antarctica Continent
(d) None

Answer

Answer: (c) Study of Antarctica Continent

Question 13.
Which program was the author a part of?
(a) Tour Program
(b) Research Program
(c) Students on Ice Program
(d) None

Answer

Answer: (c) Students on Ice Program

Question 14.
Why is Antarctica completely pure?
(a) Because of ice
(b) because of avalanches
(c) because of melting glaciers
(d) because of non-existence of humans

Answer

Answer: (d) because of non-existence of humans

Question 15.
What used to flourished on Antarctica years back?
(a) Animals
(b) Tigers
(c) Humans
(d) Fauna and flora

Answer

Answer: (d) Fauna and flora

Question 16.
What kind of atmosphere does Antarctica have?
(a) coldest
(b) driest
(c) windiest
(d) All these

Answer

Answer: (d) All these

Question 17.
What was the center of the Gondwana Supercontinent?
(a) Asia
(b) Pacific
(c) Antarctica
(d) All these

Answer

Answer: (c) Antarctica

Question 18.
How were the Himalayas formed?
(a) by a collapse in the Gondwana supercontinent
(b) by evolution
(c) by deforestation
(d) All these

Answer

Answer: (a) by a collapse in the Gondwana supercontinent

Question 19.
How has the man created ruckus on the earth?
(a) by travelling
(b) by encroaching the earth
(c) by visiting the iceland
(d) none

Answer

Answer: (b) by encroaching the earth

Question 20.
What disturbed the silence of the continent?
(a) The birds
(b) the animals
(c) the humans
(d) Avalanches

Answer

Answer: (d) Avalanches

Question 21.
Why was Tishani Doshi filled with relief and wonder when she first set his foot on the continent?
(a) to see its white expanse
(b) to see its vastness and immense white expanse
(c) to see the isolation from the rest of the world
(d) All these

Answer

Answer: (d) All these

Question 22.
What was the objective of the Students on the Ice program?
(a) to make them travel
(b) to make them see snow
(c) to make them see white expanse in the form of ice
(d) to enable them to think differently to save the planet

Answer

Answer: (d) to enable them to think differently to save the planet

Question 23.
What was Gondwana?
(a) An ancient tourist place
(b) an ancient city in Antarctica
(c) An ancient super continent
(d) None

Answer

Answer: (c) An ancient super continent

Question 24.
Who was Geoff Green?
(a) Geoff was a Fellow of the Royal Canadian Geographical Society and The Explorers Club.
(b) A scientist
(c) A traveller
(d) A tourist guide

Answer

Answer: (a) Geoff was a Fellow of the Royal Canadian Geographical Society and The Explorers Club.

Question 25.
Why has the author called her journey as Journey to the End of the Earth’?
(a) because it was too far
(b) because no human race or plants exist
(c) crosses nine time zones, six checkpoints, three water bodies and many ecospheres to reach there.
(d) All these

Answer

Answer: (c) crosses nine time zones, six checkpoints, three water bodies and many ecospheres to reach there.

Question 26.
Why is the Antarctica the right place to understand the past, present and future?
(a) because half million-year-old carbon records are trapped in its layers of ice.
(b) because of layers of ice
(c) because of cold
(d) none

Answer

Answer: (b) because of layers of ice

Question 27.
Which programme aimed to take high school students to the end of the world?
(a) The author’s delight
(b) Teachers delight
(c) School program
(d) Geoff Green’s ‘Students on Ice’ programme

Answer

Answer: (d) Geoff Green’s ‘Students on Ice’ programme

Question 28.
Why is a visit to Antartica important to understand the effect of global warming?
(a) because here one can see quickly melting glaciers and collapsing ice-shelves
(b) because it is filled with snow
(c) because it is away from urban rush
(d) None

Answer

Answer: (a) because here one can see quickly melting glaciers and collapsing ice-shelves

Question 29.
What is the purpose of The Journey to the world’s most preserved place, Antarctica?
(a) to tour the world
(b) to see the beauty of the earth
(c) to know the geography more closely
(d) to sensitize the young minds towards climatic change

Answer

Answer: (d) to sensitize the young minds towards climatic change

Question 30.
Who is the author of the lesson?
(a) Tishani Doshi
(b) Kamla Das
(c) Jane Austen
(d) Chitra Das

Answer

Answer: (a) Tishani Doshi

Question 31.
If we want to know our earth, the human race and its past, present, and future where should we go?
(a) Northern Pole
(b) Southern Pole
(c) Gondwana
(d) Antarctica Continent

Answer

Answer: (d) Antarctica Continent

Question 32.
How does the geographical phenomena help us?
(a) how small changes cause big things to happen
(b) it makes us study
(c) it helps us to watch everything closely
(d) none

Answer

Answer: (a) how small changes cause big things to happen

Question 33.
Which program was a life changing program?
(a) Tour and Travels
(b) Know Antarctica
(c) Know your earth
(d) Students on Ice

Answer

Answer: (d) Students on Ice

Question 34.
Where is the world’s geological history trapped?
(a) on southern pole
(b) On Northern Pole
(c) on Asia Continent
(d) On Antarctica Continent

Answer

Answer: (d) On Antarctica Continent

Question 35.
Where does 90% of earth’s total ice exist?
(a) Pacific region
(b) Southern oceans
(c) Northern pole
(d) Antarctica Continent

Answer

Answer: (d) Antarctica Continent

We hope the given NCERT MCQ Questions for Class 12 English Vistas Chapter 3 Journey to the End of the Earth with Answers Pdf free download will help you. If you have any queries regarding CBSE Class 12 English Journey to the End of the Earth MCQs Multiple Choice Questions with Answers, drop a comment below and we will get back to you soon.

MCQ Questions for Class 12 Physics Chapter 6 Electromagnetic Induction

January 24, 2023January 22, 2023 by Prasanna

Electromagnetic Induction Class 12 MCQs Questions with Answers

Electromagnetic Induction Class 12 MCQ Question 1.

A square of side L meters lies in the x-y plane in a region where the magnetic field is given by B = B₀ (2$\hat{\mathbf{i}}$ + 3$\hat{\mathbf{j}}$ + 4$\hat{\mathbf{k}}$) Tesla, where B₀ is constant. The magnitude of flux passing through the square is

(A) 2B₀L² Wb.
(B) 3B₀L² Wb.
(C) 4B₀L² Wb.
(D) $\sqrt{29} \mathrm{~B}_{0} \mathrm{~L}^{2}$ Wb.
Answer:
(C) 4B₀L² Wb.

Explanation:
Magnetic flux is defined as the total number of magnetic lines of force passing normally through an area placed in a magnetic field and is equal to the magnetic flux linked with that area. Square lies in X – Y plane in $\vec{B}$ so $\vec{A}$ = L² $\hat{\mathbf{k}}$

Q = B.A
= B₀(2$\hat{\mathbf{i}}$ + 3$\hat{\mathbf{j}}$+ 4$\hat{\mathbf{k}}$).(L$\hat{\mathbf{k}}$)
= B₀[2 x $\hat{\mathbf{i}}$$\hat{\mathbf{k}}$ + 3 x $\hat{\mathbf{j}}$$\hat{\mathbf{i}}$ + 4 x $\hat{\mathbf{k}}$$\hat{\mathbf{k}}$]
= B₀L²[0 + 0 + 4]
= 4B₀L²Wb.

Class 12 Physics Chapter 6 MCQ Question 2.

A loop, made of straight edges has six corners at A(0, 0, 0), B(L, 0, 0) C(L, L, 0), D(0, L, 0), E(0, L, L) and F(0,0, L). A magnetic field B=B0 ($\hat{\mathbf{i}}$ + $\hat{\mathbf{k}}$) Tesla is present in the region. The flux passing through the loop ABCDEFA (in that order) is –

(A) B₀L² Wb.
(B) 2B₀L² Wb.
(C) $\sqrt{2} \mathrm{~B}_{0} \mathrm{~L}^{2}$
(A) 4 B₀L²Wb.
Answer:
(B) 2B₀L² Wb.

Explanation:
The loop can be considered in two planes:
Electromagnetic Induction Class 12 MCQ

(i) Plane of ABCDA is in X – Y plane. So its vector
$\vec{A}$ is in Z – direction. Hence,
A₁ = $|A|$$\hat{\mathbf{k}}$ = L²$\hat{\mathbf{k}}$

(ii) Plane of DEFAD is in Y – Z p1ane
So A₂ = $|A|$$ [latex]\hat{\mathbf{k}}$ =L²$\hat{\mathbf{i}}$
A = A₁ – A₂ = L²($\hat{\mathbf{i}}$ + $\hat{\mathbf{k}}$)
B = B₀($\hat{\mathbf{i}}$ + $\hat{\mathbf{k}}$)
So, Q = B A = B₀( $\hat{\mathbf{i}}$ + $\hat{\mathbf{k}}$ )L²($\hat{\mathbf{i}}$ + $\hat{\mathbf{k}}$ = B₀ L²[$\hat{\mathbf{i}}$.$\hat{\mathbf{i}}$ + $\hat{\mathbf{i}}$.$\hat{\mathbf{k}}$ + $\hat{\mathbf{k}}$.$\hat{\mathbf{i}}$ + $\hat{\mathbf{k}}$$\hat{\mathbf{k}}$
=B₀L²[1 + 0 + 0 + 1 ] (∴cos 90°= 0)
= 2B₀L²Wb

Electromagnetic Induction MCQ Chapter 6 Question 3.

A cylindrical bar magnet is rotated about its axis in the figure. A wire is connected from the axis and is made to touch the cylindrical surface through a contact. Then

Class 12 Physics Chapter 6 MCQ

(A) a direct current flows in the ammeter A.
(B) no current flows through the ammeter A.
(C) an alternating sinusoidal current flows through the ammeter A with a time period 2jt/o).
(D) a time varying non-sinusoidal current flows through the ammeter A.
Answer:
(B) no current flows through the ammeter A.

Explanation:
The phenomenon of electromagnetic induction is used in this problem. Whenever the number of magnetic lines of force (magnetic flux) passing through a circuit changes (or a moving conductor cuts the magnetic flux), an emf is produced in the circuit (or emf induces across the ends of the conductor) is called induced emf.

The induced emf persists only as long as there is a change or cutting of flux. When cylindrical bar magnet is rotated about its axis, no change in flux linked with the circuit takes place, consequently no emf induces and hence, no current flows through the ammeter A. Hence the ammeter shows no deflection.

Chapter 6 Physics Class 12 MCQ Question 4.

There are two coils A and B as shown in figure. A current starts flowing in B as shown, when A is moved towards B and stops when A stops moving. The current in A is counter clockwise. B is kept stationary when A moves. We can infer that

Electromagnetic Induction MCQ Chapter 6

(A) there is a constant current in the clockwise direction in A.
(B) there is a varying current in A.
(C) there is no current in A.
(D) there is a constant current in the counter clockwise direction in A.
Answer:
(D) there is a constant current in the counter clockwise direction in A.

Explanation:
When coil A moves towards coil B with constant velocity, so rate of change of magnetic flux due to coil B in coil A will be constant that gives constant current in coil A in same direction as in coil B by Lenz’s law.

Physics Class 12 Chapter 6 MCQ Question 5.

Same as problem 4 except the coil A is made to rotate about a vertical axis figure. No current flows in B if A is at rest. The current in coil A, when the current in B (at t = 0) is counter-clockwise and the coil A is as shown at this instant, t – 0, is

Chapter 6 Physics Class 12 MCQ

(A) constant current clockwise.
(B) varying current clockwise.
(C) varying current counter-clockwise.
(D) constant current counter-clockwise.
Answer:
(A) constant current clockwise.

Explanation:
In this case, the direction of the induced electromotive force/induced current is determined by the Lenz’s law. According to the Lenz’s law, the direction of induced emf or current in a circuit is such that it oppose x the cause that produces it. This law is based upon law of conservation of energy.

When’the current in coil B (at t = 0) is counter-clockwise and the coil A is considered above it. he counter-clockwise flow of the current in coil B is equivalent to North Pole of magnet and magnetic field lines are eliminating upward to coil A. When coil A starts rotating at f = 0, the current in coil A is constant along clockwise direction by Lenz’s rule.

MCQ On Electromagnetic Induction Class 12 Question 6.

The polarity of induced emf is defined by

(A) Ampere’s circuital law.
(B) Biot-Savart law.
(C) Lenz’s law.
(D) Fleming’s right hand rule.
Answer:
(C) Lenz’s law.

Explanation:
According to Lenz’s law, the direction of an induced e.m.f. always opposes the change in magnetic flux that causes the e.m.f.

Ch 6 Physics Class 12 MCQ Question 7.

Lenz’s law is consequence of the law of conservation of –

(A) Charge
(B) mass
(C) energy
(D) momentum
Answer:
(C) energy

Explanation:
Lenz’s law is a consequence of the law of conservation of energy. Lenz law says that induced current always tends to oppose the cause which produces it. So work is done against opposing force. This j work is transformed into electrical energy. ; So it a consequence of law of conservation of energy.

Electromagnetic Induction MCQ Class 12 Chapter 6 Question 8.

The magnetic flux linked with a coil is given by an equation ø = 5t² + 2t + 3. The induced e.m.f. in the coil at the third second will be –

(A) 32 units
(B) 54 units
(C) 40 units
(D) 65 units
Answer:
(A) 32 units

Explanation:
Induced e.m.f = – d$/dt
= (5t² + 2t + 3) = – (10t + 2) = – 32

MCQ Of Electromagnetic Induction Chapter 6 Question 9.

The self-inductance of a solenoid of length l and area of cross-section A, with a fixed number of turns N increases as –

(A) l and A increase.
(B) l decreases and A increases.
(C) l increases and A decreases.
(D) both l and A decrease.
Answer:
(B) l decreases and A increases.

Explanation:
As we know that,
L = μ_rμ₀$\frac{\mathrm{N}^{2} \mathrm{~A}}{l}$
As L is constant for a coil,
L ∝ A and L ∝ –
As μ_r and N are constant here so, to increase L for a coil, area A must be increased and l must be decreased. So answer (B) is correct.

Important point:
The self and mutual inductance of capacitance and resistance depend on the geometry of the devices as well as permittivity/permeability of the medium.

MCQ Questions For Class 12 Physics Chapter 6 Question 10.

An iron-cored solenoid has self inductance 2.8H. When the core is removed, the self inductance becomes 2 mH. The relative permeability of the material of the core is –

(A) 1400
(B) 1200
(C) 2800
(D) 2000
Answer:
(A) 1400

Explanation:
μ_r = L/L₀ = 2.8/(2 x 10^-3) = 1400

Class 12 Physics Ch 6 MCQ Question 11.

In which of the following application, eddy current has no role to play?

(A) Electric power meters
(B) Induction furnace
(C) LED lights
(D) Magnetic brakes in trains
Answer:
(C) LED lights

Explanation:
LED is a p-n junction diode and emits light when forward biased.

Physics Chapter 6 Class 12 MCQ Question 12.

Which one of the following statements is wrong?

(A) Eddy currents are produced in a steady magnetic field.
(B) Eddy current is used to produce braking force in moving trains.
(C) Eddy currents is minimized by using a laminated core.
(D) Induction furnace uses eddy current to produce heat
Answer:
(A) Eddy currents are produced in a steady magnetic field.

Explanation:
Eddy current is produced when a metal is kept in a time-varying magnetic field.

Electromagnetic Induction MCQs Class 12 Question 13.

If the back e.m.f. induced in a coil, when current changes from 1A to zero in one millisecond, is 5 volts, the self-inductance of the coil is –

(A) 5 H
(B) 1 H
(C) 5 x 10^-3 H
(D) 5 x 10³H
Answer:
(C) 5 x 10^-3 H

Explanation:
e = – L $\frac {di}{dt}$
5 = -L x $\frac{0-1}{10^{-3}}$
∴ L = 5 x 10^-3H

Physics Class 12 MCQ Chapter 6 Question 14.

Magnetic field energy stored in a coil is

(A) Li²
(B) 1/2 Li
(C) Li
(D) 1/2 Li²
Answer:
(D) 1/2 Li²

Explanation:
If current I flows through a coil of self-inductance L, then magnetic field energy stored in it is 1/2 Li²

Class 12 Electromagnetic Induction MCQ Question 15.

If two coils of self inductance L₁and L₂ are coupled together, their mutual inductance becomes

(A) M = k $\sqrt{\mathrm{L}_{1} \mathrm{~L}_{2}}$
(B) M = k $\sqrt{\frac{\mathrm{L}_{1}}{\mathrm{~L}_{2}}}$
(C) M = k $\sqrt{\mathrm{L}_{1}+\mathrm{L}_{2}}$
(D) None of the above
Answer:
(A) M = k $\sqrt{\mathrm{L}_{1} \mathrm{~L}_{2}}$

Explanation:
If two coils of self inductance Lj and L2 are coupled together, their mutualb inductance becomes M = $\sqrt{\mathrm{L}_{1} \mathrm{~L}_{2}}$ where k = coupling constant whose value lies between 0 and 1.

MCQ Of Chapter 6 Physics Class 12 Question 16.

An inductor and a bulb are connected in series with a dc source. A soft iron core is then inserted in the inductor. What will happen to intensity of the bulb?

(A) Intensity of the bulb remains the same.
(B) Intensity of the bulb decreases.
(C) Intensity of the bulb increases.
(D) The bulb ceases to glow.
Answer:
(B) Intensity of the bulb decreases.

Explanation:
When a soft iron core is inserted in the inductor, the magnetic flux increases. According to Lenz’s law, it will be resisted by reducing the current Since the current reduces, the intensity of the bulb decreases.

Assertion And Reason Based MCQs ‘(1 Mark each)

Chapter 6 Class 12 Physics MCQ Question 1.

Assertion(A): Faraday’s laws of electromagnetic induction are consequences of law of conservation of energy.
Reason (R): The parameter LR in a L-R circuit has the dimension of time.

Answer:
(C) A is true but R is false

Explanation:
In electromagnetic induction, magnetic energy, mechanical energy are converted into electrical energy. So, Faraday’s laws of electromagnetic induction are direct consequences of law of conservation of energy. Hence assertion is true.
In a L-R circuit, L/R parameter has the dimension of time. Hence the reason is false.

Class 12 Chapter 6 Physics MCQ Question 2.

Assertion (A): When two identical loops of copper and Aluminium are rotated with same speed in the same magnetic field, the induced e.m.f. will be same.
Reason (R): Resistance of the two loops are equal.

Answer:
(C) A is true but R is false

Explanation:
Induced e.m.f. in a rotating loop in a magnetic field depends on the area of the loop, number of turns, speed of rotation and magnetic field strength. It does not depend on the material of the coil. So, when two identical loops of copper and aluminium are rotated with same speed in the same magnetic field, the induced e.m.f. will be same. So, the assertion is true. Resistance of the two loops cannot be equal. Resistance of copper loop is less than that of the aluminium loop. So, the reason is false.

Electromagnetic Induction Class 12 MCQs Question 3.

Assertion (A): Lenz’s law does not violets the principle of conservation of energy.
Reason (R): Induce e.m.f. never opposes the change in magnetic flux that causes the e.m.f.

Answer:
(C) A is true but R is false

Explanation:
Lenz’s law is based on principle of conservation of energy. So/ the assertion is true. Induced e.m.f. always opposes the change in magnetic flux that causes the e.m.f. So, the – reason is also false.

Class 12 Physics Chapter 6 MCQ Questions Question 4.

Assertion (A): If the number of turns of a coil is increased, it becomes more difficult to push a bar magnet towards the coil.
Reason (R): The difficulty faced is according to Lenz’s law.

Answer:
(A) Both A and R are true and R is the correct explanation of A

Explanation:
As it is tried to push a bar magnet towards a coil, magnetic flux increases. According to Faraday’s law induced e.m.f. is generated. As the number of turns increases, induced e.m.f. increases. According to Lenz’s law. Induced e.m.f. always opposes the change in magnetic flux that causes the induction of e.m.f. So, the induced e.m.f. will oppose the motion of the bar magnet towards the coil. As the number of turns increases, opposition increases. Hence both assertion and reason are true and the reason explains the assertion properly.

Question 5.

Assertion (A): When the magnetic flux changes around a metallic conductor, the eddy current is produced.
Reason (R): Electric potential determines the flow of charge.

Answer:
(B) Both A and R are true but R is NOT the correct explanation of A

Explanation:
Change in flux induces emf in conductor which generates eddy current. So assertion is true.
Electric potential determines the flow of charge. So reason is also true. But reason is not the proper explanation of generation of eddy current.

Question 6.

Assertion (A): The cores of electromagnets are made of soft iron.
Reason (R): Coercivity of soft iron is small.

Answer:
(A) Both A and R are true and R is the correct explanation of A

Explanation:
The core of an electromagnet should be such that it gets magnetized easily. Also, it loses magnetism easily as soon as the magnetizing field is removed. Soft iron has this property. So, soft iron is used as the core electromagnet. So the assertion is true. Coercivity is a measure of the ability of a ferromagnetic substance to withstand external magnetic field without becoming demagnetized. For soft iron, it should be very low. Coercivity is low for soft iron. So, reason is also true. Also, reason properly explains the assertion.

Question 7.

Assertion (A): Mutual inductance becomes maximum when coils are wound on each other.
Reason (R): Mutual inductance is independent of orientation of coils.

Answer:
(C) A is true but R is false

Explanation:
Mutual inductance depends on size, number of turns, relative position and relative orientation of the 2 coils. So, when coils are wound on each other, the mutual inductance will be maximum. So, assertion is true, But the reason is false.

Question 8.

Assertion (A): Self inductance may be called the inertia of electricity.
Reason (R): Due to self inductance, opposing induced e.m.f. is generated in a coil as a result of change in current or magnetic flux linked with the coil.

Answer:
(B) Both A and R are true but R is NOT the correct explanation of A

Explanation:
Inertia is defined as the tendency of an object to resists its change of state of motion. Induced e.m.f. in a coil is changed by the change in current or magnetic flux. The property by which a coil opposes these parameters to incur any change in induced e.m.f. is known as self-inductance. Hence, self inductance may be called the inertia of electricity. So, the assertion and reason both are true but reason cannot explain why so happens.

Case-Based MCQs

Attempt any 4 sub-parts out of 5. Each sub-part carries 1 mark.

I. Read the following text and answer the following questions on the basis of the same:

Bottle Dynamo:

A bottle dynamo is a small generator to generate electricity to power the bicycle light.
Is is not a dynamo. Dynamo generates DC but a bottle dynamo generates AC. Newer models are now available with a rectifier. The available DC can power the light and small electronic gadgets. This is also known as sidewall generator since it operates using a roller placed on the sidewall of bicycle tyre. When the bicycle is in motion, the dynamo roller is engaged and electricity is generated as the type spins the roller.

When engaged, a dynamo requires the bicycle rider to exert more effort to maintain a given speed than would otherwise be necessary when the dynamo is not present or disengaged. Bottle dynamos can be completely disengaged during day time when cycle light is not in use. In wet conditions, the roller on a bottle dynamo can slip against the surface of the type, which interrupts the electricity generated. This cause the lights to go out intermittently.

Physics Class 12 Chapter 6 MCQ

Question 1.

Why bottle dynamo is not a dynamo ?

(A) It generates AC only
(B) It generates DC only
(C) It looks like a bottle
(D) It requires no fuel to operate
Answer:
(A) It generates AC only

Explanation:
Dynamo generates DC. But bottle dynamo generates AC. So, it is not a dynamo in that sense. But, it generates electricity for bicycle light.

Question 2.

Can you recharge the battery of your mobile phone with the help of bottle dynamo ?

(A) Yes
(B) No
(C) Yes, when a rectifier is used
(D) Yes, when a transformer is used
Answer:
(C) Yes, when a rectifier is used

Explanation:
Newer models of bottle generators are now available with a rectifier. DC available from such bottle generator can be used directly for charging mobile phone. Otherwise with the old models, a rectifier is to be attached to convert AC to DC.

Question 3.

Bottle generator generates electricity:

(A) when fuel is poured in the bottle.
(B) when cycle is in motion.
(C) when it is mounted properly.
(D) when wind blows.
Answer:
(B) when cycle is in motion.

Explanation:
Bottle generator is also known as sidewall generator since it operates using a roller placed on the sidewall of bicycle tyre. When the bicycle is in motion, the dynamo roller is engaged and electricity is generated as the tyre spins the roller.

Question 4.

Bulb of bicycle light glows:

(A) with AC supply only.
(B) with DC supply only.
(C) with both AC and DC supply.
(D) only when AC supply is rectified.
Answer:
(C) with both AC and DC supply.

Explanation:
Normal lamps work with both AC and DC. So, bottle generators of older model or newer model can be directly used for bicycle lamp.

Question 5.

Which one of the following is not an advantages of newer model of bottle dynamo ?

(A) Works intermittently when it roller slips on type
(B) Small electronic gadgets can be charged
(C) Can be easily disengaged during day time
(D) Requires no fuel
Answer:
(A) Works intermittently when it roller slips on type

Explanation:
In wet conditions, the roller on a bottle dynamo (old model or new model) can slip against the surface of the tyre, which interrupts the electricity generated. This causes the lights to go out intermittently. This is not an advantage.

II. Read the following text and answer the following questions on the basis of the same:

Electromagnetic damping:

Take two hollow thin cylindrical pipes of equal internal diameters made of aluminium and PVC, respectively. Fix them vertically with clamps on retort stands. Take a small cylindrical magnet having diameter slightly smaller than the inner diameter of the pipes and drop it through each pipe in such a way that the magnet does not touch the sides of the pipes during its fall.

You will observe that the magnet dropped through the PVC pipe takes the same time to come out of the pipe as it would take when dropped through the same height without the pipe. Now instead of PVC pipe use an aluminium pipe. Note the time it takes to come out of the pipe in each case. You will see that the magnet takes much longer time in the case of aluminium pipe.

Why is it so ? It is due to the eddy currents that are generated in the aluminium pipe which oppose the change in magnetic flux, i.e., the motion of the magnet. The retarding force due to the eddy currents inhibits the motion of the magnet. Such phenomena are referred to as electromagnetic damping. Note that eddy currents are not generated in PVC pipe as its material is an insulator whereas aluminium is a conductor. This effect was discovered by physicist Foucault (1819-1868).

Question 1.

Eddy current is generated in a:

(A) metallic pipe.
(B) PVC pipe.
(C) glass pipe.
(D) wooden pipe.
Answer:
(A) metallic pipe.

Explanation:
Eddy currents are not generated in non-conductor/insulator. Eddy currents are generated in conductor/metal.

Question 2.

Eddy current was first observed by:

(A) Helmhotlz
(B) Foucault
(C) D’Arsonval
(D) Shock ley
Answer:
(B) Foucault

Explanation:
The generation of eddy current was discovered by physicist Foucault (1819-1869).

Question 3.

What is electromagnetic damping ?

(A) Generation of electromagnetic wave during the passage of a magnet through a metal pipe
(B) Change of the direction of propagation of electromagnetic wave due to a variable magnetic flux
(C) Change of the frequency of electromagnetic wave due to a variable magnetic flux
(D) To slow down the motion of a magnet moving through a metal pipe due to electromagnetically induced current.
Answer:
(D) To slow down the motion of a magnet moving through a metal pipe due to electromagnetically induced current.

Explanation:
The retarding force due to the eddy currents inhibits the motion of the magnet in a metal pipe. This phenomena is known as electromagnetic damping.

Question 4.

To observe electromagnetic damping a magnet should be dropped through a metal pipe and:

(A) the magnet should not touch inner wall of the pipe.
(B) the magnet should touch the inner wall of the pipe.
(C) it does not matter whether the magnet touches the inner wall of the pipe or not.
(D) the magnet should be larger in size than the diameter of the pipe.
Answer:
(A) the magnet should not touch inner wall of the pipe.

Explanation:
To observe electromagnetic damping, a magnet should be dropped through a metal pipe and the magnet should not touch the inner wall of the pipe.

Question 5.

A piece of wood and a bar magnet of same dimension is dropped through an aluminium pipe. Which of the following statements is true ?

(A) The piece of wood will take more time to come out from the pipe.
(B) The bar magnet will take more time to come out from the pipe.
(C) Both will take same time to come out from the pipe.
(D) The time required will depend on the mass of the wooden piece and the mass of the bar magnet.
Answer:
(B) The bar magnet will take more time to come out from the pipe.

Explanation:
When a piece of wood and a bar magnet of same dimension is dropped through an aluminium pipe, the bar magnet will take more time to come out from the pipe due to electromagnetic damping.

II. Read the following text and answer the following questions on the basis of the same:

Spark coil:
The principle of electromagnetic induction was discovered by Michael Faraday in 1831. Induction coils were used widely in electrical experiments and for medical therapy during the last half of the 19th century, eventually leading to the development of radio in the 1890’s. The spark coil designed on the principle of electromagnetic induction was the heart of the earliest radio transmitters.

Marconi used a spark coil designed by Heinrich Rhumkorff in his early experiments. An induction coil or “spark coil” is a type of electrical transformer used to produce high-voltage pulses from a low-voltage (DC) supply. To create the flux changes necessary to induce voltage in the secondary coil, the direct current in the primary coil is repeatedly interrupted by a vibrating mechanical contact called interrupter.

MCQ On Electromagnetic Induction Class 12

The spark scoil consists of two coils of insulated wire wound around a common iron core. One coil, called the primary coil, is made from relatively few (tens or hundreds) turns of coarse wire. The other coil, the secondary coil typically consists of up to a million turns of fine wire (up to 40 gauge). An electric current is passed through the primary, creating a magnetic field. Because of the common core, most of the primary’s flux couples with the secondary. When the primary current is suddenly interrupted, the magnetic field rapidly collapses.

This causes a high voltage pulse to be developed across the secondary terminals due to electromagnetic induction. Because of the large number of turns in the secondary coil, the secondary voltage pulse is typically many thousands of volts. This voltage is sufficient to create an electric spark, to jump across an air gap separating the secondary’s output terminals. For this reason, this induction coils are also called spark coils.

To operate the coil continually, the DC supply current must be repeatedly connected and disconnected. To do that, a magnetically activated vibrating arm called an interrupter is used which rapidly connects and breaks the current flowing into the primary coil. The interrupter is mounted on the end of the coil next to the iron core. When the power is turned on, the produced magnetic field attracts the armature.

When the armature has moved far enough, contacts in the primary circuit breaks and disconnects the primary current. Disconnecting the current causes the magnetic field to collapse and create the spark. A short time later the contacts reconnect, and the process repeats. An arc which may form at the interrupter contacts is undesirable. To prevent this, a capacitor of 0.5 to 15 IUF is connected across the primary coil.

Question 1.

The heart of the radio transmitters of Marconi was a

(A) spark coil.
(B) toroid.
(C) RF tuning coil.
(D) Van de Graff generator.
Answer:
(A) spark coil.

Explanation:
The spark coil designed on the principle of electromagnetic induction was the heart of the earliest radio transmitters. Marconi usecl a spark coil designed by Heinrich Rhumkorff in his early experiments.

Question 2.

Spark coil is a type of –

(A) electrical generator.
(B) electrical transformer.
(C) static electricity generator.
(D) large capacitor.
Answer:
(B) electrical transformer.

Explanation:
A spark coil is a type of 1 electrical transformer used to produce high- 1 voltage pulses from a low-voltage (DC) g supply. To create the flux changes necessary to induce voltage in the secondary coil, the direct current in the primary coil is repeatedly interrupted by a vibrating mechanical contact called interrupter.

Question 3.

Which of the following statements is correct?

(A) Spark coil consists of two coils of insulated wire. Primary coil, is made from relatively few turns of fine wire. The secondary coil consists of up to a million turns of coarse wire.
(B) Spark coil consists of two coils of insulated wire. Primary coil, is made from a (tens or million turns of coarse wire. The secondary coil consists of up to a few turns of fine wire.
(C) Spark coil consists of two coils of insulated wire. Primary coil, is made from relatively few turns of coarse wire. The secondary coil consists of up to a million turns of fine wire.
(D) Spark coil consists of two coils of insulated wire. Both primary and secondary coil, is made from a million turns of fine wire.
Answer:
(C) Spark coil consists of two coils of insulated wire. Primary coil, is made from relatively few turns of coarse wire. The secondary coil consists of up to a million turns of fine wire.

Explanation:
The spark coil consists of two coils of insulated wire wound around a common iron core. One coil, called the primary coil, is made from relatively few (tens or hundreds) turns of coarse wire. The other coil, the secondary coil typically consists of up to a million turns of fine wire (up to 40 gauge).

Question 4.

Why most of the primary’s flux couples with the secondary in spark coil?

(A) Since the primary coil is wound on the secondary coil
(B) Since the primary coil is of thick wire
(C) Since the core is common
(D) None of the above
Answer:
(C) Since the core is common

Explanation:
The spark coil designed on the principle of electromagnetic induction was die heart of the earliest radio transmitters. Marconi used a spark coil designed by Heinrich Rhumkorff in his early experiments.

Question 5.

What is the function of interrupter in a spark coil?

(A) To rapidly connect and break the current flowing into the primary coil
(B) To rapidly connect and break the current flowing into the secondary coil
(C) to control the formation of spark
(D) None of the above
Answer:
(A) To rapidly connect and break the current flowing into the primary coil

Explanation:
To operate the coU continually, the DC supply current must be repeatedly connected and disconnected. To do that, a magnetically activated vibrating arm called an interrupter is used which rapidly connects and breaks the current flowing into the primary coil.

MCQ Questions for Class 12 Physics with Answers

MCQ Questions for Class 12 Political Science Chapter 4 India’s External Relations with Answers

January 24, 2023January 21, 2023 by Prasanna

Check the below NCERT MCQ Questions for Class 12 Political Science Chapter 4 India’s External Relations with Answers Pdf free download. MCQ Questions for Class 12 Political Science with Answers were prepared based on the latest exam pattern. We have provided India’s External Relations Class 12 Political Science MCQs Questions with Answers to help students understand the concept very well. https://mcqquestions.guru/mcq-questions-for-class-12-political-science-chapter-4-part-b/

India’s External Relations Class 12 MCQs Questions with Answers

India’s External Relations Class 12 MCQ Question 1.
“The foreign policy of a country is the outcome of her economic policy” these remarks were made by:
(a) Indira Gandhi
(b) Jawaharlal Nehru
(c) Morarji Desai
(d) Charan Singh

Answer

Answer: (b) Jawaharlal Nehru

India’s External Relations MCQ Chapter 4 Class 12 Question 2.
Bandung Conference was held in the year:
(a) 1954
(b) 1955
(c) 1956
(d) 1957

Answer

Answer: (b) 1955

India External Relations Class 12 MCQ Question 3.
Bangladesh emerged as an independent nation in:
(a) January 1972
(b) December 1971
(c) March 1971
(d) November 1971

Answer

Answer: (b) December 1971

Class 12 Political Science Chapter 4 India’s External Relations MCQ Question 4.
China made a sudden attack on India in:
(a) August 1962
(b) September 1962
(c) October 1962
(d) September 1965

Answer

Answer: October 1962

MCQ Of India’s External Relations Class 12 Question 5.
The Architect of Non-alignment is:
(a) Pt. Nehru
(b) Indira Gandhi
(c) Y. B. Chavan
(d) Atal Behari Vajpayee

Answer

Answer: (a) Pt. Nehru

Class 12 Political Science India’s External Relations MCQ Question 6.
Match the following:

(a) The goal of India’s foreign policy in the period 1950-1964	(I) Tibetan spiritual leader who crossed over to India
(b) Panchsheel	(II) Preservation of territorial integrity, sovereignty, and economic development
(c) Bandung Conference	(III) Five principles of peaceful coexistence
(d) Dalai Lama	(IV) Led to the establishment of NAM

Answer

Answer:

(a) The goal of India’s foreign policy in the period 1950-1964	(II) Preservation of territorial integrity, sovereignty, and economic development
(b) Panchsheel	(III) Five principles of peaceful coexistence
(c) Bandung Conference	(IV) Led to the establishment of NAM
(d) Dalai Lama	(I) Tibetan spiritual leader who crossed over to India

Indian External Relations MCQ Chapter 4 Class 12 Question 7.
In the formulation of foreign policy, what was Pt. Jawaharlal Nehru’s first priority?

Answer

Answer: National interest was the first priority of Pt. Jawaharlal Nehru.

Class 12 India’s External Relations MCQ Chapter 4 Question 8.
In which year McMahon Line boundary line was determined between India and China?

Answer

Answer: In 1914, McMahon Line was determined.

India’s External Relations MCQs Class 12 Question 9.
Who proposed the partition of Kashmir?

Answer

Answer: M.C. Naughton.

MCQ Of India External Relations Class 12 Chapter 4 Question 10.
In which year, who declared the five principles of Panchsheel?

Answer

Answer: In 1954, Pt. Jawaharlal Nehru declared five principles of Panchsheel.

Chapter 4 India’s External Relations MCQ Question 11.
In which year China invaded India?

Answer

Answer: China attacked India in 1962.

MCQs Of India’s External Relations Class 12 Chapter 4 Question 12.
After the Chinese revolution in 1949, which country was the first to recognize the Communist Government?

Answer

Answer: India was the first country to recognize the Communist Government.

Question 13.
What do you mean by Panchsheel?

Answer

Answer: The word ‘Pancbsheel’ stands for five principles of conduct and behaviour.

Question 14.
Write one basic principle of India’s foreign policy.

Answer

Answer: The most important basic principle of India’s foreign policy is non-alignment.

Question 15.
Where the first Non-aligned Summit was held?

Answer

Answer: The first Non-aligned Summit was held in Belgrade in 1961.

Question 17.
Which is a major issue of dispute between India and Pakistan?

Answer

Answer: Kashmir is a major issue of dispute between India and Pakistan.

Write ‘True’ or ‘False’ against each of these statements.

Question 18.
Non-alignment allowed India to gain assistance both from U.S.A. and U.S.S.R.

Answer

Answer: True

Question 19.
India’s relationship with her neighbours has been strained from the beginning.

Answer

Answer: True

Question 20.
The Cold War has affected the relationship between India and Pakistan.

Answer

Answer: True

Question 21.
The treaty of Peace and Friendship in 1971 was the result of India’s closeness to the U.S.A.

Answer

Answer: False

We hope the given NCERT MCQ Questions for Class 12 Political Science Chapter 4 India’s External Relations with Answers Pdf free download will help you. If you have any queries regarding CBSE Class 12 Political Science India’s External Relations MCQs Multiple Choice Questions with Answers, drop a comment below and we will get back to you soon.

Alternating Current Class 12 MCQs Questions with

If the rms current in a 50 Hz AC circuit is 5 A, the value of the current 1/300 s after its value becomes zero is

An alternating current generator has an internal resistance Rg and an internal reactance Xg. It is used to supply power to a passive load consisting of a resistance Rg and a reactance XL. For maximum power to be delivered from the generator to the load, the value of XL is equal to

When a voltage measuring device is connected to AC mains, the meter shows the steady input voltage of 220 V. this means

When frequency of applied alternating voltage very high then

Relation between r.m.s. voltage and instantaneous voltage of an AC

The heat produced in a given resistance in a given time by the sinusoidal current I sin cof will be the same as heat produced by a steady current of magnitude

An A.C. source is connected to a resistive circuit. Which of the following statements is true?

In which of the following circuit power dissipation is maximum?

To reduce the resonant frequency in an L – C – R series circuit with a generator

Which of the following combinations should be selected for better tuning of an L-C-R circuit used for communication?

With increase in frequency of an A.C. supply, the impedance of a series L-C-R circuit

The sharpness of tuning of a series LCR circuit at resonance is measured by Q factor of the circuit which is given by

At resonance, the impedance in series LCR circuit is

The power factor of series LCR circuit at resonance is –

When a capacitor C is charged to a certain potential and connected to an inductor L, then frequency of energy oscillation is given by –

The output of a step-down transformer is measured to be 24 V when connected to a 12 W Light bulb. The value of the peak current is

The underlying principle of transformer is –

The core of a transformer is laminated as

If rotational velocity of an armature is doubled, emf generated in a generator will be

Quantity that remains unchanged in a transformer is –

…………… increases in step-down transformer.

The efficiency of transformer is very high because

Assertion (A): An alternating current does not show any magnetic effect. Reason (R): Alternating current changes direction with time.

Assertion (A): Capacitor blocks dc and allows ac to pass. Reason (R): Capacitive reactance is inversely proportional to frequency.

Assertion (A): VRMSvalue of an alternating voltage V = 4\(\sqrt{2}\) sin 314t is 4 volt. Reason (R): Peak value of the alternating voltage is 442 volt.

Assertion (A): Both ac and dc can be measured by hot wire instrument. Reason (R): Hot wire instrument is based on the principal of magnetic effect of current.

Assertion (A): The dimension of L/R is time. Reason (R): Time constant (L/R) should be increased to reduce the rate of increase of current through a solenoid.

Assertion (A): At resonance, the current becomes minimum in a series LCR circuit. Reason (R): At resonance, voltage and current are out of phase in a series LCR circuit.

Assertion (A): When capacitive reactance is less than the inductive reactance in a series LCR circuit, e.m.f. leads the current. Reason (R): The angle by which alternating voltage leads the alternating current in series RLC circuit is given by tan φ = \(\frac{X_{L}-X_{C}}{R}\)

Assertion (A): Quality factor of a series LCR circuit is Q = \(\frac{1}{R} \sqrt{\frac{L}{C}}\) Reason (R): As bandwidth decreases, Q increases in a resonant LCR circuit.

Assertion (A): Principle of operation of AC generator is electromagnetic induction. Reason (R): Resistance offered by inductor for AC is zero.

Assertion (A): An alternator is a machine which converts mechanical energy into electrical energy. Reason (R): When a coil rotates in a magnetic field an e.m.f. is induced in it.

Assertion (A): A transformer does not work on DC. Reason (R): DC neither change direction nor magnitude.

Assertion (A): A step-up transformer converts input low AC voltage to output high AC voltage. Reason (R): It violate the law of conservation of energy.

Name the phenomenon involved in tuning a radio set to a particular radio station.

Resonance may occur in:

Resonance frequency is equal to:

Resonance occurs only when:

Capacitor used in radio set for tuning is a:

Which of the following statement is true for long distance transmission of electricity?

Super-conducting transmission line has the following advantages:

Why does stepping up voltages reduce power loss?

Oil transfers heat from transformer winding by the process of:

Flush point of an oil is –

What is the relationship among core loss, hysteresis loss and eddy current loss?

Which of the following losses in transformer is also known as no-load loss?

Which of the following losses in transformer is also known as variable loss?

How hysteresis loss can be reduced?

MCQ Questions for Class 12 Physics with Answers

Human Reproduction Class 12 MCQ Questions With Answers

Spot the odd one out from the following structures with reference to the male reproductive system.

Which one of the following is not a male accessory gland?

The vas deferens receives duct from the seminal vesicle and opens into urethra as

Urethral meatus refers to the

Seminal plasma, the fluid part of semen, is on tributed by

Identify the odd one from the following.

Prostate glands are located below

Lower narrow end of uterus is called

The third stage of parturition is called “after-birth”. In this stage

Which of the following contains the actual genetic part of a sperm?

Identify the wrong statement from the following.

The immature male germ cells undergo division to produce sperms by the process of spermatogenesis. Choose the correct one with reference to above.

Spermiation is the process of the release of sperms from

Match between the following representing parts of the sperm and their functions and choose the correct option.

Mature Graafian follicle is generally present in the ovary of a healthy human female around stet.

Which among the following has 23 chromosomes?

The membranous cover of the ovum at ovulation is

At what stage of life is oogenesis initiated in a human female?

A human female reaches menopause around the age of

Layers of an ovum from outside to inside is

Choose the incorrect statement from the following.

Acrosomal reaction of the sperm occurs due to

Morula is a developmental stage

Match the following and choose the correct options.

Which of the following hormones is not secreted by human placenta?

The early-stage human embryo distinctly possesses

Gastrula is the embryonic stage in which

Implantation takes place after fertilization.

Cleavage differs from mitosis in lacking

Assertion (A): An alternating current does not show any magnetic effect.
Reason (R): Alternating current changes direction with time.

Assertion (A): Capacitor blocks dc and allows ac to pass.
Reason (R): Capacitive reactance is inversely proportional to frequency.

Assertion (A): V_RMSvalue of an alternating voltage V = 4\(\sqrt{2}\) sin 314t is 4 volt.
Reason (R): Peak value of the alternating voltage is 442 volt.

Assertion (A): Both ac and dc can be measured by hot wire instrument.
Reason (R): Hot wire instrument is based on the principal of magnetic effect of current.

Assertion (A): The dimension of L/R is time.
Reason (R): Time constant (L/R) should be increased to reduce the rate of increase of current through a solenoid.

Assertion (A): At resonance, the current becomes minimum in a series LCR circuit.
Reason (R): At resonance, voltage and current are out of phase in a series LCR circuit.

Assertion (A): When capacitive reactance is less than the inductive reactance in a series LCR circuit, e.m.f. leads the current.
Reason (R): The angle by which alternating voltage leads the alternating current in series RLC circuit is
given by tan φ = \(\frac{X_{L}-X_{C}}{R}\)

Assertion (A): Quality factor of a series LCR circuit is Q = \(\frac{1}{R} \sqrt{\frac{L}{C}}\)
Reason (R): As bandwidth decreases, Q increases in a resonant LCR circuit.

Assertion (A): Principle of operation of AC generator is electromagnetic induction.
Reason (R): Resistance offered by inductor for AC is zero.

Assertion (A): An alternator is a machine which converts mechanical energy into electrical energy.
Reason (R): When a coil rotates in a magnetic field an e.m.f. is induced in it.

Assertion (A): A transformer does not work on DC.
Reason (R): DC neither change direction nor magnitude.

Assertion (A): A step-up transformer converts input low AC voltage to output high AC voltage.
Reason (R): It violate the law of conservation of energy.

Assertion (A): Urethra in human male act as a urinogenital canal.
Reason (R): Urethra carries only urine while sperms are carried by vasa deferentia only.

Assertion (A) : In human male, testes are extraabdominal and lie in scrotal sacs.
Reason (R): Scrotum protects the testes.

Assertion (A): The region outside the seminiferous tubules is called interstitial spaces, which contain Leydig’s cells.
Reason (R): Leydig’s cells synthesize and secrete testicular hormones called androgen.

Assertion (A): Large members of mitochondria are present in middle piece of sperm.
Reason (R): Numerous mitochondria in the middle piece of sperm produce energy which is required for their movement.

Assertion (A): The secretory phase in the human menstrual cycle is also called the luteal phase.
Reason (R): During the luteal phase development of corpus luteum and secretion of progesterone occurs.

Assertion (A): Vasa efferentia develop from rete testis.
Reason (R): Sperm conduction takes place by the ciliary current.

Assertion (A): The fusion of sperm and ovum to form zygote is called fertilization.
Reason (R): It occurs at ampullary isthmic junction of the fallopian tube.

Assertion (A): Oxytocin helps in parturition.
Reason (R): Oxytocin acts on uterine muscle and causes expulsion of the fetus.

Assertion (A): Endometrium is a mucosal tissue made up of two layers.
Reason (R): It is a inner lining of the uterus. Each month it thickens and renews itself, preparing for pregnancy.

Assertion (A): The Leydig cells of testis are present outside the seminiferous tubules.
Reason (R): Testis helps to synthesize and secrete hormones called androgens.

Assertion: The gamete formed in males determines the sex of the offspring.
Reason: Sex determination in humans depends upon cumulative effect of some genes of X and Y chromosomes.

Assertion (A): All copulations do not lead to the fertilization and pregnancy.
Reason (R): Fertilisation can occur only if the ovum and sperms are transported simultaneously to the ampullary isthmic junction.

Assertion (A): Blastocyst undergoes gastrulation to form three germinal layers.
Reason (R): This involves cell movements (morphogenetic movement) that help to attain new shape and morphology of embryo.

A square of side L meters lies in the x-y plane in a region where the magnetic field is given by B = B₀ (2\(\hat{\mathbf{i}}\) + 3\(\hat{\mathbf{j}}\) + 4\(\hat{\mathbf{k}}\)) Tesla, where B₀ is constant. The magnitude of flux passing through the square is

The magnetic flux linked with a coil is given by an equation ø = 5t² + 2t + 3. The induced e.m.f. in the coil at the third second will be –

If two coils of self inductance L₁and L₂ are coupled together, their mutual inductance becomes

Assertion(A): Faraday’s laws of electromagnetic induction are consequences of law of conservation of energy.
Reason (R): The parameter LR in a L-R circuit has the dimension of time.

Assertion (A): When two identical loops of copper and Aluminium are rotated with same speed in the same magnetic field, the induced e.m.f. will be same.
Reason (R): Resistance of the two loops are equal.

Assertion (A): Lenz’s law does not violets the principle of conservation of energy.
Reason (R): Induce e.m.f. never opposes the change in magnetic flux that causes the e.m.f.

Assertion (A): If the number of turns of a coil is increased, it becomes more difficult to push a bar magnet towards the coil.
Reason (R): The difficulty faced is according to Lenz’s law.

Assertion (A): When the magnetic flux changes around a metallic conductor, the eddy current is produced.
Reason (R): Electric potential determines the flow of charge.

Assertion (A): The cores of electromagnets are made of soft iron.
Reason (R): Coercivity of soft iron is small.

Assertion (A): Mutual inductance becomes maximum when coils are wound on each other.
Reason (R): Mutual inductance is independent of orientation of coils.

Assertion (A): Self inductance may be called the inertia of electricity.
Reason (R): Due to self inductance, opposing induced e.m.f. is generated in a coil as a result of change in current or magnetic flux linked with the coil.