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 a switch `S` as shown in the circuit diagram. With switch `S` open, the null position is obtained at a distance of `51 cm` from `P`.
(i) Calculate the potential gradient of the potentiometer wire.
(ii) Find the emf of cell `E_(1)`.
(iii) When switch `S` is closed, will the null point move toward `P` or toward `Q`? Give reason for your answer.

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