Physics - Current Electricity Question with Solution | TestHub

Length of the potentiometer wire, $L=4$ m

Potential difference across the wire, $V=2$ V

Potential gradient of the wire, $k=\frac{V}{L}=\frac{2}{4}=0.5$ V/m

Balancing length for the cell, $l=80$ cm $=0.8$ m

The e.m.f. of the cell is given by $E=kl$

$E=0.5\times 0.8=0.40$ V

Answer: $0.40$ V