Question

The length of potentiometer wire is 4m and is connected in series with an accumulator. The e.m.f. (unknown) of a cell balances against 1.5 m length of wire. If the length of potentiometer wire is doubled, then the new balancing length of wire will be

• A. 4.5 m
• B. 1.5 m
• C. 0.75 m
• D. 3 m

Hint:

In potentiometer problems, the balancing length is directly proportional to the length of the wire. Doubling the wire length doubles the balancing length.

Answer 1

The Correct Option is D

Step 1: Understanding the relation.
In a potentiometer, the balancing length is directly proportional to the length of the wire. If the length of the wire is doubled, the balancing length will also double. Step 2: Calculation of new balancing length.
Initially, the balancing length is 1.5 m. If the length of the wire is doubled, the new balancing length will be: \[ \text{New balancing length} = 2 \times 1.5 = 3 \, \text{m} \] Thus, the correct answer is (D) 3 m.