JEE Main - Wheatstone bridge and metre bridge Question Bank with Options

1. Which of the following is a direct consequence of the metre bridge wire having a uniform cross-sectional area and being made of a material with a constant resistivity?

A) The resistance per unit length is constant.

B) The voltage drop per unit length is constant.

C) The current per unit length is constant.

D) The potential difference across the wire is constant.

2. In a metre bridge, if the known resistance is 100 Ω and the balance point is at 60 cm, the unknown resistance is:

A) 60 Ω

B) 150 Ω

C) 166.7 Ω

D) 40 Ω

3. If the galvanometer shows zero deflection, it means the potential at the two terminals of the galvanometer is:

A) Maximum

B) Minimum

C) Equal

D) Zero

4. The metre bridge is less accurate for measuring resistances when the balance point is:

A) Near 50 cm

B) Near 0 cm or 100 cm

C) Exactly at 50 cm

D) Far from the ends

5. In a Wheatstone bridge, if the resistances P, Q, R, and S are increased by 10% each, the balance condition:

A) Changes

B) Remains the same

C) Depends on the battery voltage

D) May change or remain the same

6. If the galvanometer resistance is very high, the current through the galvanometer when the bridge is slightly unbalanced will be:

A) High

B) Low

C) Zero

D) Variable

7. The ratio of unknown resistance to known resistance in a metre bridge is equal to the ratio of:

A) The length of the wire from the jockey to the left end to the length from the jockey to the right end.

B) The length of the wire from the jockey to the right end to the length from the jockey to the left end.

C) The total length of the wire to the length from the jockey to the left end.

D) The total length of the wire to the length from the jockey to the right end.

8. In a metre bridge, if the unknown resistance is much larger than the known resistance, the balance point will be:

A) Near the 0 cm mark.

B) Near the 100 cm mark.

C) Near the 50 cm mark.

D) Indeterminate.

9. If in a Wheatstone bridge, the galvanometer resistance is increased, it leads to:

A) Increased sensitivity.

B) Decreased sensitivity.

C) No change in sensitivity.

D) Instability of the bridge.

10. Which of the following is NOT a source of error in a metre bridge experiment?

A) Non-uniformity of the wire.

B) Contact resistance.

C) Parallax error in reading the length.

D) Resistance of the galvanometer.

11. To measure a very low resistance using a metre bridge, one should:

A) Place it in the left gap and use a high known resistance.

B) Place it in the right gap and use a low known resistance.

C) Place it in the left gap and use a low known resistance.

D) Place it in the right gap and use a high known resistance.

12. If the length of the metre bridge wire is increased to 2 metres, while keeping the resistances the same, the balance point will:

A) Shift towards the unknown resistance.

B) Shift towards the known resistance.

C) Remain at the same relative position.

D) Be affected by the battery voltage.

13. The condition for balancing a Wheatstone bridge (P/Q = R/S) is derived from:

A) Ampere's Law

B) Kirchhoff's Current Law

C) Kirchhoff's Voltage Law

D) The principle of superposition

14. If a small resistance is added in series with the galvanometer in a Wheatstone bridge, the sensitivity:

A) Increases

B) Decreases

C) Remains unchanged

D) Becomes zero

15. In a metre bridge, the terminal resistances at the ends of the wire can be neglected if:

A) The resistances in the gaps are very large.

B) The resistances in the gaps are very small.

C) The balance point is very close to the ends.

D) The balance point is near the center of the wire.

16. A Wheatstone bridge is used to measure an unknown resistance X. The known resistances are P=100Ω, Q=200Ω, R=300Ω. What should be the value of S for the bridge to be balanced?

A) 150 Ω

B) 600 Ω

C) 50 Ω

D) 400 Ω

17. If the galvanometer resistance is very low in a Wheatstone bridge, the sensitivity:

A) Increases

B) Decreases

C) Remains unchanged

D) Becomes zero

18. In a metre bridge experiment, an error in measuring the length L directly affects:

A) The resistance of the known resistor.

B) The resistance of the unknown resistor.

C) The ratio of resistances.

D) The balance condition.

19. If the resistances in the four arms of a Wheatstone bridge are 10 Ω, 20 Ω, 30 Ω, and 60 Ω, is the bridge balanced?

A) Yes, because 10/20 = 30/60

B) No, because 10*60 != 20*30

C) Yes, because 10+20 = 30+60

D) No, because 10/30 != 20/60

20. The metre bridge is essentially a practical application of:

A) Ohm's Law

B) Kirchhoff's Laws

C) The principle of Wheatstone bridge

D) Faraday's Laws

21. If the galvanometer in a Wheatstone bridge shows a deflection of 'd' when the battery polarity is reversed, and 'd'' when one of the resistances is changed, the sensitivity is related to:

A) d/d'

B) d'/d

C) d+d'

D) d-d'

22. In a metre bridge, the jockey should be slid gently along the wire to:

A) Prevent damage to the wire.

B) Ensure good electrical contact.

C) Avoid scratching the wire and creating non-uniformity.

D) Increase the resistance of the wire.

23. When is a Wheatstone bridge most sensitive?

A) When all resistances are very small.

B) When all resistances are very large.

C) When the resistances in the arms are of comparable magnitude.

D) When one resistance is very large and the others are small.

24. If the galvanometer resistance is very high in a Wheatstone bridge, the sensitivity:

A) Increases

B) Decreases

C) Remains unchanged

D) Becomes infinite

25. A metre bridge is more suitable for measuring resistances in the range of:

A) Milliohms

B) Ohms to a few kilo-ohms

C) Megaohms

D) Gigaohms

26. In a Wheatstone bridge, if the battery voltage is doubled, the balance condition:

A) Changes

B) Remains the same

C) Is no longer possible

D) Depends on the resistances

27. If a resistance of 5 ohms in the left gap of a metre bridge gives a balance point at 30 cm, what is the resistance in the right gap?

A) 3.5 ohms

B) 7.14 ohms

C) 11.67 ohms

D) 16.67 ohms

28. Which of the following is a limitation of the Wheatstone bridge?

A) It cannot measure very low resistances accurately.

B) It cannot measure very high resistances accurately.

C) It requires a very sensitive galvanometer for all measurements.

D) It is only suitable for AC circuits.

29. The metre bridge can be used to measure the resistance of a galvanometer by:

A) Placing it in the unknown arm and using a known resistance.

B) Placing it in the known arm and using an unknown resistance.

C) Using it as the galvanometer in a second Wheatstone bridge.

D) Connecting it in series with the battery.

30. In a metre bridge, if the battery polarity is reversed, the balance point will:

A) Shift towards the end with the unknown resistance.

B) Shift towards the end with the known resistance.

C) Remain at the same position.

D) Disappear.

31. If one of the resistances in the Wheatstone bridge is increased, what happens to the condition for balance?

A) The ratio of other resistances must change.

B) The balance point shifts.

C) The bridge becomes unbalanced.

D) All of the above

32. A galvanometer is used in a Wheatstone bridge primarily to:

A) Supply current

B) Measure voltage

C) Detect the presence and direction of current

D) Measure resistance directly

33. Contact resistances at the ends of the metre bridge wire can cause errors in measurement. To minimize this error, the unknown resistance should be:

A) Very small

B) Very large

C) Of moderate value, such that the balance point is near the center

D) Equal to the known resistance

34. If, in a balanced Wheatstone bridge, the galvanometer resistance is increased, the sensitivity of the bridge:

A) Increases

B) Decreases

C) Remains unchanged

D) Becomes zero

35. The sensitivity of a Wheatstone bridge is maximum when:

A) All resistances are very low.

B) All resistances are very high.

C) The resistances are comparable.

D) The resistances are widely different.

36. In a metre bridge, the resistance of the wire is not uniform. This will lead to:

A) An incorrect measurement of resistance.

B) A shift in the balance point.

C) A change in galvanometer sensitivity.

D) No effect on the measurement.

37. If the resistances in the gaps of a metre bridge are swapped, and the new balance point is at 60 cm, what is the ratio of the resistances?

A) 1:2

B) 2:1

C) 1:1

D) 3:2

38. What is the primary disadvantage of a metre bridge compared to a Wheatstone bridge?

A) It can only measure small resistances.

B) It can only measure large resistances.

C) It is less accurate for resistances near the ends of the wire.

D) It requires a more sensitive galvanometer.

39. The metre bridge is used to determine:

A) The resistance of a conductor

B) The specific resistance of a conductor

C) The electromotive force (EMF) of a cell

D) The internal resistance of a cell

40. If the balance point in a metre bridge is found at 40 cm from the left end, and the resistance in the left gap is 10 ohms, what is the resistance in the right gap?

A) 10 ohms

B) 15 ohms

C) 20 ohms

D) 25 ohms

41. In a metre bridge, if the unknown resistance is placed in the left gap and the known resistance is placed in the right gap, and the balance point is obtained at length L, then the unknown resistance R_x is given by:

A) R_x = R_k * (L / (100-L))

B) R_x = R_k * ((100-L) / L)

C) R_x = R_k * (L / 100)

D) R_x = R_k * (100 / L)

42. Why is Manganin or Eureka preferred for the metre bridge wire?

A) High resistivity and low temperature coefficient of resistance

B) Low resistivity and high temperature coefficient of resistance

C) High conductivity and low temperature coefficient of resistance

D) Low conductivity and high temperature coefficient of resistance

43. The wire used in a metre bridge is typically made of:

A) Copper

B) Aluminum

C) Manganin or Eureka

D) Iron

44. In a metre bridge experiment, the jockey is moved along the wire until the galvanometer shows no deflection. This point is called the:

A) Null point

B) Balance point

C) Zero deflection point

D) All of the above

45. A metre bridge works on the principle of:

A) Heating effect of current

B) Magnetic effect of current

C) Wheatstone bridge

D) Electromagnetic induction

46. Which of the following is a necessary condition for a Wheatstone bridge to be balanced?

A) All resistances must be equal.

B) The ratio of resistances in the first two arms must be equal to the ratio of resistances in the other two arms.

C) The sum of resistances in opposite arms must be equal.

D) The product of resistances in adjacent arms must be equal.

47. If the galvanometer in a Wheatstone bridge shows deflection, it means the bridge is:

A) Balanced

B) Unbalanced

C) Partially balanced

D) Irrelevant

48. In a Wheatstone bridge circuit, if the galvanometer is replaced by a voltmeter, and the bridge is balanced, what will be the reading of the voltmeter?

A) Maximum possible voltage

B) Minimum possible voltage

C) Zero volts

D) Voltage equal to the source voltage

49. A Wheatstone bridge is balanced. If the galvanometer shows no deflection, it implies that:

A) The current through the galvanometer is maximum.

B) The current through the galvanometer is zero.

C) The potential difference across the galvanometer is maximum.

D) The potential difference across the galvanometer is zero.

50. In a Wheatstone bridge, the four arms have resistances P, Q, R, and S. The bridge is balanced when:

A) P/Q = R/S

B) P/R = Q/S

C) P/S = Q/R

D) P*Q = R*S

Wheatstone bridge and metre bridge - Question Bank