Pyq- Wheatstones Bridge, Meter Bridge & Potentiometer

• Question 1

The correct answer is: (D)

The null point is found at 40 cm from the left end when resistance X is balanced against another resistance Y. If the resistance X is shunted by a resistance 4X, the null point will be shifted by 10 cm.

• Question 2

The correct answer is: (C)

The balancing length AJ = 300 cm. When the jockey is moved from A to C, the balancing length decreases by 60 cm.

Therefore, R = 300 × 60/240 = 36 Ω.

• Question 3

The correct answer is: (A)

In the Wheatstone bridge, the resistances P and Q are interchanged. The change in the bridge balance will be no change.

The reason is that the bridge balance depends on the ratio of resistances P/Q and R/S. When P and Q are interchanged, the ratio P/Q remains the same. Therefore, the bridge balance will not change.