Question

Consider the potentiometer circuit arranged as in figure (32-E29). The potentiometer wire is 600 cm long, (a) At what distance from the point A should the jockey touch the wire to get zero deflection in the galvanometer ? (b) If the jockey touches the wire at a distance of 560 cm from A, what will be the current in the galvanometer ?

Answer 1

(a) Let the jockey divide the 600 cm length into two parts as shown below:

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

Therefore,

(b) Since, 600cm=15r, therefore, 560 cm will be equal to 14r. The diagram of the equivalent circuit is given below.

By solving the above equation we get the value of I₂=3E/22r

Answer 2

Resistance per unit length =15r/6