# Current Electricity MCQ Questions for Class 12 Physics Chapter 3 with Answers

Find here the NCERT chapter-wise Multiple Choice Questions from Class 12 Physics book Chapter 3 Current Electricity with Answers Pdf free download. This may assist you to understand and check your knowledge about the chapters. Students also can take a free test of the Multiple Choice Questions of Current Electricity. Each question has four options followed by the right answer. These MCQ Questions are selected supported by the newest exam pattern as announced by CBSE.

## Q1. In parallel combination of n cells, we obtain

(i) more voltage
(ii) more current
(iii) less voltage
(iv) less current

(ii) more current

(i) 3
(ii) 4
(iii) 5
(iv) 6

(ii) 4

## Q3. Two cells of emf’s approximately 5 V and 10 V are to be accurately compared using a potentiometer of length 400 cm.

(i) The battery that runs the potentiometer should have voltage of 8 V.
(ii) 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.
(iii) The first portion of 50 cm of wire itself should have a potential drop of 10 V.
(iv) Potentiometer is usually used for comparing resistances and not voltages.

(ii) 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.

## Q4. A resistance R is to be measured using a meter bridge. A student chooses the standard resistance S to be 100 Ω. He finds the null point at l1 = 2.9 cm. He is told to attempt to improve the accuracy. Which of the following is a useful way?

(i) He should measure l1 more accurately.
(ii) He should change S to 1000 Ω and repeat the experiment.
(iii) He should change S to 3 Ω and repeat the experiment.
(iv) He should give up hope of a more accurate measurement with a meter bridge.

(iii) He should change S to 3 Ω and repeat the experiment.

## Q5. In the equation AB = C, A is the current density, C is the electric field, Then B is

(i) resistivity
(ii) conductivity
(iii) potential difference
(iv) resistance

(i) resistivity

(i) 12.5 Q
(ii) 13.5 Q
(iii) 14.5 Q
(iv) 16.5 Q

(i) 12.5 Q

(i) 2
(ii) 3
(iii) 4
(iv) 5

(ii) 3

## Q8. A resistance R is to be measured using a meter bridge. Student chooses the standard resistance S to be 100 Ω He finds the null point at l1 = 2.9 cm. He is told to attempt to improve the accuracy. Which of the following is a useful way?

(i) He should measure l1 more accurately.
(ii) He should change Sto 1000 Ω and repeat the experiment.
(iii) He should change S to 3 Ω and repeat the experiment.
(iv) He should give up hope of a more accurate measurement with a meter bridge.

(iii) He should change S to 3 Ω and repeat the experiment.

## Q9. Two cells of emfs approximately 5 V and 10 V are to be accurately compared using a potentiometer of length 400 cm.

(i) The battery that runs the potentiometer should have voltage of 8 V.
(ii) 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.
(iii) The first portion of 50 cm of wire itself should have a potential drop of 10 V.
(iv) Potentiometer is usually used for comparing resistances and not voltages.

(ii) 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.

## Q10. A current passes through a wire of nonuniform cross-section. Which of the following quantities are independent of the cross-section?

(i) The charge crossing
(ii) Drift velocity
(iii) Current density
(iv) Free-electron density

(iv) Free-electron density

## Q11. In the series combination of two or more than two resistances

(i) the current through each resistance is same.
(ii) the voltage through each resistance is same.
(iii) neither current nor voltage through each re-sistance is same.
(iv) both current and voltage through each resis¬tance are same.

(i) the current through each resistance is same.

(i) 12 Ω
(ii) 120 Ω
(iii) 12 KΩ
(iv) 120 MΩ

(iii) 12 KΩ

## Q13. Consider a current carrying wire current I in the shape of a circle. Note that as the current progresses along the wire, the direction of j (current density) changes in an exact manner, while die current/remain unaffected. The agent that is essentially responsible for is

(i) source of emf.
(ii) electric field produced by charges accumulated on the surface of wire.
(iii) the charges just behind a given segment of wire which push them just the right way by repulsion.
(iv) the charges ahead.

(ii) electric field produced by charges accumulated on the surface of wire.

## Q14. Kirchhoff’s junction rule is a reflection of

(i) conservation of current density vector.
(ii) conservation of charge.
(iii) the fact that the momentum with which a charged particle approaches a junction is unchanged (as a vector) as the charged particle leaves the junction.
(iv) the fact that there is accumulation of charges at a junction.

(ii) conservation of charge.

## Q15. When no current is passed through a conductor,

(i) the free electrons do not move
(ii) the average speed of a free electron over a large period of time is not zero
(iii) the average velocity of a free electron over a large period of time is zero
(iv) the average of the velocities of all the free electrons at an instant is non zero

(iv) the average of the velocities of all the free electrons at an instant is non zero

## Q16. An electric heater is connected to the voltage supply. After few seconds, current gets its steady value then its initial current will be

(i) equal to its steady current
(ii) slightly higher than its steady current
(iii) slightly less than its steady current
(iv) zero

(ii) slightly higher than its steady current

## Q17. Specific resistance of ali metals is mostly affected by:

(i) temperature
(ii) pressure
(iii) magnetic field
(iv) volume

(i) temperature

## Q18. Which of the following is wrong? Resistivity of a conductor is

(i) independent of temperature.
(ii) inversely proportional to temperature.
(iii) independent of dimensions of conductor.
(iv) less than resistivity of a semiconductor.

(i) independent of temperature.

## Q19. Which of the following characteristics of electrons determines the current in a conductor?

(i) Drift velocity alone.
(ii) Thermal velocity alone.
(iii) Both drift velocity and thermal velocity.
(iv) Neither drift nor thermal velocity.

(i) Drift velocity alone.

## Q20. The current which is assumed to be flowing in a circuit from positive terminal to negative, is called

(i) direct current
(ii) pulsating current
(iii) conventional current
(iv) alternating current

(iii) conventional current

## Q21. In a Wheatstone bridge if the battery and galvanometer are interchanged then the deflection in galvanometer will

(i) change in previous direction
(ii) not change
(iii) change in opposite direction
(iv) none of these.

(ii) not change

## Q22. The example of a non-ohmic resistance is:

(i) copper wire
(ii) fi lament lamp
(iii) carbon resistor
(iv) diode

(iv) diode

(i) 0.5 ohm
(ii) 1.5 ohm
(iii) 1.25 ohm
(iv) 4/5 ohm

(i) 0.5 ohm

## Q24. Masses of three wires are in the ratio 1 : 3 : 5 and their lengths are in the ratio 5 : 3 : 1. The ratio of their electrical resistance is

(i) 1 : 3 : 5
(ii) 5 : 3 : 1
(iii) 1 : 15 : 125
(iv) 125 : 15 : 1

(iv) 125 : 15 : 1

(i) V
(ii) V
(iii) T
(iv) T

(ii) V

## Q26. When a metal conductor connected to left gap of a meter bridge is heated, the balancing point

(i) shifts towards right
(ii) shifts towards left
(iii) remains unchanged
(iv) remains at zero

(i) shifts towards right

## Q27. The specific resistance of a rod of copper as compared to that of thin wire of copper is :

(i) less
(ii) more
(iii) same
(iv) depends upon the length and area of cross-section of the wire

(iii) same

## Q28. The resistivity of alloy manganin is

(i) Nearly independent of temperature
(ii) Increases rapidly with increase in temperature
(iii) Decreases with increase in temperature
(iv) Increases rapidly with decrease in temperature

(i) Nearly independent of temperature

(i) 1154 K
(ii) 1127 K
(iii) 600 K
(iv) 1400 K

(ii) 1127 K

## Q30. A current passes through a resistor. If K1 and K2 represent the average kinetic energy of the conduction electrons and the metal ions respectively then

(i) K1 < K2 (ii) K1 = K2 (iii) K1 > K2
(iv) any of these three may occur

(iii) K1 > K2

## Q31. A charge is moving across a junction, then

(i) momentum will be conserved.
(ii) momentum will not be conserved.
(iii) at some places momenturii will be conserved and at some other places momentum will not be conserved.
(iv) none of these.

(iv) none of these.

(i) halved
(ii) doubled
(iii) unchanged

(i) halved

(i) 12.5 Q
(ii) 13.5 Q
(iii) 14.5 Q
(iv) 16.5 Q

(i) 12.5 Q

(i) E = J/k
(ii) E = J k
(iii) E = k/J
(iv) k = J E

(ii) E = J k

## Q35. At temperature 0K, the germanium behaves as a / an

(i) conductor
(ii) insulator
(iii) super-conductor
(iv) ferromagnetic

(ii) insulator

(i) Cu
(ii) Constantan