A potentiometer wire PQ of 1 m length is connected to a standard cell `E_(1)` . Another cell`E_(2)` of emf `1.02` V is connected with a resistance ‘r’ and switch S (as shown in figure). With switch S open, the null position is obtained at a distance of 49 cm from Q. The potential gradient in the potentiometer wire is:

Options

A. `0.03` V/cm
B. `0.02` V/cm
C. `0.04`V/cm
D. `0.01` V/cm

Answer

B

Explanation

PQ = 1 m
QJ = 49 cm
` :. ` PJ = 51 cm
` v/l = (1.02)/51 = 0.02 ` v/cm