Question

A potentiometer wire is 4 m long and potential difference of 3V is maintained between the ends. The e.m.f. of the cell which balances against a length of 100 cm of the poteniometer wire is

• A. \(0.25\) V
• B. \(0.50\) V
• C. \(0.75\) V
• D. \(1.0\) V

Hint:

The potential gradient is the total voltage over the wire length, and the emf equals gradient times balancing length.

Answer 1

The Correct Option is C

Step 1: Use proportion.
100 cm is one quarter of 400 cm.

Step 2: Potential.
The potential across a quarter of the wire is one quarter of 3 V.

Step 3: Compute.
$3/4 = 0.75$ V.

Final Answer:
Option (C). \[ \boxed{0.75\text{ V}} \]