Question

A potentiometer wire of length 10 m is connected in series with a battery. The emf of a call balances against 250 cm length of wire. If length of potentiometer wire is increased by 1 m, then new balancing length of wire will be:

• A. 2.00 m
• B. 2.25 m
• C. 2.50 m
• D. 2.75 m

Answer 1

The correct option is D 2.75 m

Given,

$l_1=2.5m,L_1=10m$

$L_2=11m$

For potentiometer,

$\frac{l}{L}=\frac{V}{E}$

Since $V$ and $E$ is constant,

$l_2=l_1\frac{L_2}{L_1}$

$=2.5\times \frac{11}{10}$

$=2.75m$