In a potentiometer circuit, a cell of EMF 1.5 V gives balance point at 36 cm length of wire. If another cell of EMF 2.5 V replaces the first cell, then at what length of the wire, the balance point occurs?
(1) 60 cm
(2) 21.6 cm
(3) 64 cm
(4) 62 cm
Solution
We have, $\frac {E_1}{E_2}=\frac {l_1}{l_2}$
$\Rightarrow \frac {1.5}{2.5}=\frac {36}{l}$
$\Rightarrow l=60$ cm
Answer: (1)