NCERT Class 12 Chapter 3 Physics Current Electricity MCQ

NCERT Class 12 Chapter 3 Physics Current Electricity MCQ | Questions & Answers: With the help of this article, you can take up the NCERT Class 12 Chapter 3 Physics Current Electricity MCQ Quiz. By the end of taking the test, you will get to know the expertise you have in the respective area of interest. Good luck!

Page 1 of 3

1. The cold junction of a thermocouple is maintained at 10ºC. No thermo e.m.f. is developed when the hot junction is maintained at 530ºC. The neutral temperature is

A. 260ºC

B. 265ºC

C. 270ºC

D. 520ºC

2. An electric heater is connected to the voltage supply. After few seconds, current gets its steady value then its initial current will be

A. equal to its steady current

B. slightly higher than its steady current

C. slightly less than its steady current

D. zero

3. The resistivity of alloy manganin is

A. Nearly independent of temperature

B. Increases rapidly with increase in temperature

C. Decreases with increase in temperature

D. Increases rapidly with decrease in temperature

4. V-I graph of which material shows the straight line

A. Silicon

B. Silver

C. Germanium

D. Gallium

5. Consider a current carrying wire (current I) in the shape of a circle

A. source of emf

B. electric field produced by charges accumulated on the surface of wire

C. the charges just behind a given segment of wire which push them just the right way by repulsion

D. the charges ahead

6. In the series combination of two or more than two resistances

A. the current through each resistance is same.

B. the voltage through each resistance is same.

C. neither current nor voltage through each re-sistance is same.

D. both current and voltage through each resis¬tance are same

7. In a Wheatstone bridge if the battery and galvanometer are interchanged then the deflection in galvanometer will

A. change in previous direction

B. not change

C. change in opposite direction

D. none of these.

8. The following fig. shows I-V graph for a given metallic wire at two temperatures T1 and T2.Then,

CBSE Class12 Physics Current Electricity (8Q)

A. Temperature T₂ is more

B. Temperature T₂ is more

C. T₁ is same as T₂

D. None of the above

9. Combine three resistors 5 Q, 4.5 Q and 3 Q in such a way that the total resistance of this combination is maximum

A. 12.5 Q

B. 13.5 Q

C. 14.5 Q

D. 16.5 Q

10. Combine three resistors 5 Q, 4.5 Q and 3 Q in such a way that the total resistance of this combination is maximum

A. 12.5 Q

B. 13.5 Q

C. 14.5 Q

D. 16.5 Q

Page 2 of 3

11. Two cells of emfs approximately 5 V and 10 V are to be accurately compared using a potentiometer of length 400 cm.

A. The battery that runs the potentiometer should have voltage of 8V

B. The battery of potentiometer can have a voltage of 15 V and R adjusted so that the potential drop across the wire slightly exceeds 10 V.

C. The first portion of 50 cm of wire itself should have a potential drop of 10 V.

D. Potentiometer is usually used for comparing resistances and not voltages

12. When a metal conductor connected to left gap of a meter bridge is heated, the balancing point

A. shifts towards right

B. shifts towards left

C. remains unchanged

D. remains at zero

13. How many electrons are flowing per second through a section of a conductor corresponding to current of 1A?

A. 7. 00 × 10¹⁸

B. 6.25 × 10¹⁸

C. 3.25 × 10¹⁶

D. 75 × 10¹⁷

14. Which of the following characteristics of electrons determines the current in a conductor?

A. Drift velocity alone

B. Thermal velocity alone

C. Both drift velocity and thermal velocity

D. Neither drift nor thermal velocity

15. A cell having an emf E and internal resistance r is connected across a variable external resistance R. As the resistance R is increased, the plot of potential difference V across R is given by

CBSE Class12 Physics Current Electricity (15Q

CBSE Class12 Physics Current Electricity (15Q

A. (a)

B. (b)

C. (c)

D. (d)

16. In a potentiometer of 10 wires, the balance point is obtained on the 7th wire. To shift the balance point to 9th wire, we should

A. decrease resistance in the main circuit.

B. increase resistance in the main circuit.

C. decrease resistance in series with the cell whose emf is to be measured.

D. increase resistance in series with the cell whose emf is to be determined

17. 1 ohm is equal to

A. 1 volt per ampere

B. 1 ampere per millivolt

C. 1 milliampere per volt

D. 1 ampere per volt

18. The cold junction of a thermocouple is maintained at 10ºC. No thermo e.m.f. is developed when the hot junction is maintained at 530ºC. The neutral temperature is

A. 260ºC

B. 265ºC

C. 270ºC

D. 520ºC

19. In parallel combination of n cells, we obtain

A. more voltage

B. more current

C. less voltage

D. less current

20. AB is a wire of potentiometer with the increase in the value of resistance R, the shift in the balance point J will be
Physics MCQs for Class 12 with Answers Chapter 3 Current Electricity 6

A. towards B

B. towards A

C. remains constant

D. first towards B then back towards A

Page 3 of 3

21. Which of the following is an ohmic conductor?

A. LED

B. Thyristor

C. diode

D. Metal conductor

22. In a large building, there are 15 bulbs of 40 W, 5 bulbs of 100 W, 5 fans of 80 W and 1 heater of 1 kW. The voltage of electric mains is 220 V. The minimum capacity of the main fuse of the building will be:

A. 8A

B. 10 A

C. 12 A

D. 14 A

23. If n cells each of emf e and internal resistance r are connected in parallel, then the total emf and internal resistance will be

CBSE Class12 Physics Current Electricity (23Q)

CBSE Class12 Physics Current Electricity (23Q)

A. (a)

B. (b)

C. (c)

D. (d)

24. A charge is moving across a junction, then

A. momentum will be conserved.

B. momentum will not be conserved.

C. at some places momenturii will be conserved and at some other places momentum will not be conserved.

D. none of these.

25. Choose the correct option
Assertion : When current through a bulb decreases by 0.5%, the glow of bulb decreases by 1%.
Reason : Glow (Power) which is directly proportional to square of current

A. If both Assertion and Reason are correct and Reason is the correct explanation of Assertion.

B. If both Assertion and Reason are correct, but Reason is not the correct explanation of Assertion.

C. If Assertion is correct but Reason is incorrect.

D. If both the Assertion and Reason are incorrect.