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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?
A
21.6 cm
B
64 cm
C
62 cm
D
60 cm
Detailed Solution
For a potentiometer, $E \propto \ell$: $\frac{E_1}{E_2} = \frac{\ell_1}{\ell_2}$
$\frac{1.5}{2.5} = \frac{36}{\ell_2} \Rightarrow \ell_2 = 36 \times \frac{5}{3} = 60$ cm