Question

Consider the potentiometer circuit arranged as in figure. The potentiometer wire is $600$cm long. At what distance from the point A should the jockey touch the wire to get zero deflection in the galvanometer?

Answer 1

Let the jockey divide the $600$ cm length into two parts

$\frac{E}{2}=(15-x){rI}_1=E=2=(15-x){rI}_1$

$E=(15-x){rI}_1+(1+x){rI}_1=16{rI}_1$

$2(15-x)=16$

$2x=14=x=7$

Let the jockey be placed at a distance of $y$ cm from the left

$\frac{y}{600-y}=\frac{15-x}{x}=\frac{8}{7}$

$7y=4800-8y$

$y=\frac{4800}{15}=320cm$