Current Electricity Mock Test

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Quiz: Current Electricity – Progressive Test
Total questions: 400
Questions in this round: 50
Time allotted: 70 minutes
Pass score: 60%
Total rounds: 8
Current round: 1^st
Rounds passed: 0 / 8
Weakest rounds: None
Rounds attempted: 0

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Quiz: Current Electricity – Certificate Challenge
Total questions: 400
Questions to attempt: 100 random
Time allotted: 100 minutes
Certificate pass score: 70%
Random questions: Yes
Certificate: Yes
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Progressive Test — Guest First Round

Current Electricity – Progressive Test

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1 / 50

1. Two resistors and are connected in parallel across a fixed voltage . The current division relation gives the current through as

2 / 50

2. The meter-bridge balance point is at from the left end with unknown in the left gap and in the right gap. The value of is

3 / 50

3. A metallic conductor is carrying a steady current. Its macroscopic neutrality means that

a) the conductor has no mobile conduction electrons

b) electrons stop drifting once current begins

c) lattice and electron charges balance overall

d) only positive ions carry the current through the metal

4 / 50

4. A cell gives terminal potential difference when no current is drawn. When a current of is drawn, the terminal potential difference becomes . The internal resistance of the cell is

5 / 50

5. Assertion: Adding one more resistor in parallel with an existing resistor combination reduces the equivalent resistance.
Reason: The new branch gives an additional path for current at the same potential difference.

a) Assertion is false, but Reason is true

b) Both Assertion and Reason are true, but Reason does not explain Assertion

c) Assertion is true, but Reason is false

d) Both Assertion and Reason are true, and Reason explains Assertion

6 / 50

6. Consider the following statements about current in a circuit.
I. Electric current is a scalar quantity in ordinary circuit analysis.
II. A direction is still associated with current flow in a wire.
III. Conventional current in a metal is always along electron drift.

a) I, II, and III

b) I and III only

c) I and II only

d) II and III only

7 / 50

7. Consider the following statements about drift velocity in the Drude model.
I. The drift speed magnitude is proportional to if is constant.
II. The relaxation time represents an average time between collisions.
III. Electron drift is along because conventional current is along .

a) II and III only

b) I, II, and III

c) I and II only

d) I and III only

8 / 50

8. During a meter-bridge experiment, the balance point for in the left gap and in the right gap is very close to the left end. A better experimental adjustment is to

a) press the jockey harder to increase contact resistance

b) make the bridge wire non-uniform

c) remove the galvanometer permanently

d) interchange and

9 / 50

9. A total of identical cells is arranged as parallel rows, each row containing cells in series. Each cell has internal resistance , and the external resistance is . The grouping that gives the best internal-resistance match is

10 / 50

10. The SI unit of conductivity is

11 / 50

11. A metal wire and a semiconductor sample are both heated. The most likely qualitative comparison is

a) both show increasing resistance for the same microscopic reason

b) metal resistance usually increases, while semiconductor resistance usually decreases

c) metal resistance usually decreases, while semiconductor resistance usually increases

d) both must keep exactly constant resistance if dimensions are unchanged

12 / 50

12. A fuse of resistance carries a current of for just before melting. The heat produced in the fuse wire during this interval is

13 / 50

13. A switch in a torch is opened after the torch was glowing. The lamp goes off mainly because

a) the cell loses all its stored charge instantly

b) the conducting path becomes incomplete

c) the resistance of the wire becomes exactly zero

d) the lamp changes from a conductor into an insulator

14 / 50

14. During a potentiometer experiment, no balance point is obtained on the wire for a given test cell. A likely reason is that

a) the test cell has no positive terminal

b) the galvanometer resistance has become exactly zero

c) the jockey is first placed at the midpoint as a rule

d) full-wire drop is less than test-cell emf

15 / 50

15. In deriving the Wheatstone bridge balance condition, the key reason the galvanometer branch can be ignored at balance is that

a) all four bridge resistances become equal

b) the galvanometer resistance becomes infinite only at balance

c) galvanometer branch has zero potential difference

d) the battery current becomes zero

16 / 50

16. For a potentiometer circuit, the driving cell in the primary circuit must have emf greater than the emf of the test cell mainly to ensure that

a) the test cell is short-circuited

b) full wire can provide the balancing potential drop

c) the balance point always lies exactly at

d) the galvanometer resistance becomes zero

17 / 50

17. For a metallic conductor, resistance generally increases when temperature rises because

a) electrons lose their negative charge at high temperature

b) the number of positive ions moving through the wire increases greatly

c) resistivity becomes independent of material at high temperature

d) increased lattice vibrations produce stronger electron scattering

18 / 50

18. Study the table and identify the row that gives an unsuitable potentiometer conclusion.

Row	Observation	Conclusion
P	Longer balance length on the same wire	Larger balanced potential difference
Q	No current through galvanometer at balance	Null condition is reached
R	Smaller potential gradient	Greater sensitivity, if balance remains on the wire
S	Loaded balance length greater than open-circuit balance length for a real discharging cell	Normal effect of internal resistance

a) Row R

b) Row Q

c) Row P

d) Row S

19 / 50

19. A Wheatstone bridge is balanced when

a) the current through every arm is zero

b) galvanometer current is zero

c) the battery current is zero

d) all four resistances are necessarily equal

20 / 50

20. For three resistors , , and connected in parallel, the equivalent resistance satisfies

21 / 50

21. The resistivity form of microscopic Ohm's law is

22 / 50

22. A fuse wire protects a circuit mainly because it

a) has very high melting point and never heats up

b) melts when excessive current causes heating

c) is connected in parallel with every appliance

d) increases the supply voltage during overload

23 / 50

23. A cell with internal resistance supplies a current of . Its terminal potential difference is

24 / 50

24. A device is rated at . If it is connected to and its resistance is assumed unchanged, the power consumed is

25 / 50

25. Consider the following statements about resistivity and conductivity.
I. has unit .
II. .
III. Resistivity of a material changes automatically when the wire is cut into two equal halves, even if temperature is unchanged.

a) I and II only

b) II and III only

c) I, II, and III

d) I and III only

26 / 50

26. Identical cells are connected to a very small external resistance. A parallel grouping may be preferred because it

a) forces all cells to oppose one another

b) reduces the equivalent internal resistance

c) increases the equivalent internal resistance

d) makes the equivalent emf equal to zero

27 / 50

27. A galvanometer of resistance gives full-scale deflection at . It is to be converted into an ammeter of range . The required shunt resistance is approximately

28 / 50

28. A battery has parallel rows, each row containing identical cells in series. Each cell has emf and internal resistance . If the external resistance is , the current supplied by the battery is

29 / 50

29. In choosing a material for a standard resistance coil, an alloy is often preferred because it usually has

a) high resistivity with a small temperature coefficient

b) very low resistivity and very large temperature coefficient

c) zero resistivity at room temperature

d) negative resistance at all ordinary temperatures

30 / 50

30. A real cell with internal resistance is connected to an external resistor . The terminal potential difference of the cell is

31 / 50

31. A carbon resistor has colour bands grey, red, brown, and silver. The resistance range allowed by its tolerance is

a) to

b) to

c) to

d) to

32 / 50

32. The microscopic form of Ohm's law for an isotropic conducting material is

33 / 50

33. When the series resistance in the primary circuit is increased, the potentiometer wire has a smaller potential gradient. For the same test cell, the new balance length becomes

a) unchanged in all cases

b) zero

c) smaller

d) larger

34 / 50

34. Study the table for a Wheatstone bridge.

Row	Condition	Meaning
P		Bridge is balanced
Q	Galvanometer current	Null deflection
R	All four resistances must be equal	Necessary for balance
S	Galvanometer junction potentials are equal	No potential difference across galvanometer

The unsuitable row is

a) Row Q

b) Row P

c) Row S

d) Row R

35 / 50

35. Study the table and identify the device most likely to be non-ohmic.

Row	Device or material	Expected - behavior
P	Metal resistor at constant temperature	Linear
Q	Semiconductor diode	Non-linear and direction-dependent
R	Uniform metallic wire with fixed temperature	Linear
S	Ohmic resistor used within rating	Linear

a) Row S

b) Row P

c) Row Q

d) Row R

36 / 50

36. A cell of internal resistance is connected to a parallel combination of and . The power dissipated in the branch is

37 / 50

37. The working principle of a potentiometer is that, for a uniform wire carrying steady current, the potential drop along the wire is

a) inversely proportional to its length

b) directly proportional to its length

c) proportional to the square of the length

d) independent of length

38 / 50

38. In a series combination of resistors, the same current flows through every resistor because

a) each resistor must have the same potential difference

b) each resistor has the same resistance

c) there is only one conducting path for charge flow

d) the equivalent resistance is always zero

39 / 50

39. A graph of versus for an ohmic resistor is a straight line through the origin. If the slope of the line is , the resistance is

40 / 50

40. Match the potentiometer quantity with its meaning.

Quantity	Meaning
P.	1. Balance length for a given cell
Q.	2. Potential drop per unit length
R.	3. Balanced emf or potential difference
S.	4. Length difference related to internal voltage drop in cell experiment

a) P-1, Q-2, R-3, S-4

b) P-4, Q-1, R-2, S-3

c) P-2, Q-3, R-1, S-4

d) P-2, Q-1, R-3, S-4

41 / 50

41. The potential gradient of a potentiometer is . A cell balances at . The emf of the cell is

42 / 50

42. A resistor and a resistor are connected in parallel across a source. The current through the branch is

43 / 50

43. A potentiometer wire of length and resistance is connected in series with a resistor and a driving cell of negligible internal resistance. A test cell balances at . The emf of the test cell is

44 / 50

44. With a potential gradient of , a cell balances at . If the same cell is connected across a resistance and the balance length falls to , the terminal voltage of the cell under load is

45 / 50

45. Two resistors and are connected in series across a source. If the current is , the total power dissipated in the two resistors is

46 / 50

46. A sample has , , and . Its conductivity is

47 / 50

47. Two cells balance at and on the same potentiometer wire. The ratio of their emfs is

48 / 50

48. For the graph described below, answer the question that follows.

A graph of potential difference on the vertical axis against current on the horizontal axis is a straight line through the origin. The line passes through the point .

The resistance represented by the graph is

49 / 50

49. A resistor obeys Ohm's law and has . When the current through it is increased from to at constant temperature, the increase in potential difference is

50 / 50

50. Assertion: In a balanced Wheatstone bridge, the resistance of the galvanometer does not affect the balance condition.
Reason: At balance, the potential difference across the galvanometer is zero.

a) Both Assertion and Reason are true, but Reason does not explain Assertion

b) Both Assertion and Reason are true, and Reason explains Assertion

c) Assertion is false, but Reason is true

d) Assertion is true, but Reason is false

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Current Electricity Mock Test – Class 12 Physics

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