Question

When a potential difference of 2 V is applied across the ends of a wire of $5m$ length, a current of $1A$ flows through it. Calculate the resistance across the ends of the wire if its length is doubled.

• A. 2 ohm
• B. 3 ohm
• C. 4 ohm
• D. 5 ohm

Answer 1

The correct option is C

4 ohm

Given: Potential difference $V=2V$

Current $I=1A$.

Let the resistance be $R$.

Resistance of $5m$ length wire, $R=\frac{V}{I}=\frac{2}{1}=2$ ohm

When the length of the wire is doubled, resistance of the wire also gets doubled since $R$ is directly proportional to length of the wire. So, resistance of the wire of length $10m$ will be $4$ ohm.