JEE Main - Wheatstone bridge and metre bridge Online Test (MCQ Quiz)

1. 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

2. 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.

3. 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

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

A) Balanced B) Unbalanced C) Partially balanced D) Irrelevant

5. 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.

6. A metre bridge works on the principle of:

A) Heating effect of current B) Magnetic effect of current C) Wheatstone bridge D) Electromagnetic induction

7. 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

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

A) Copper B) Aluminum C) Manganin or Eureka D) Iron

9. 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

10. 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)

11. 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

12. 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

13. 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.

14. 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

15. 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.

16. 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.

17. 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

18. 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

19. 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

20. 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

21. 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.

22. 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.

23. 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.

24. 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

25. 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

26. 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

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

A) Increases B) Decreases C) Remains unchanged D) Becomes infinite

28. 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.

29. 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.

30. 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'

31. 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

32. 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

33. 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.

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

A) Increases B) Decreases C) Remains unchanged D) Becomes zero

35. 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

36. 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.

37. 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

38. 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

39. 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.

40. 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.

41. 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.

42. 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.

43. 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.

44. 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.

45. 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

46. 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

47. 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

48. 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

49. 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

50. 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.

Wheatstone bridge and metre bridge - Online Test

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