In the given potentiometer circuit, the resistance of the potentiometer wire `AB` is `R_(0). C` is a cell of internal resistandce `r`. The galvanometer `G` does not give zero following cannot be a reason for this ?

Options

A. `r gt R_(0)`
B. `R gt gt R_(0)`
C. Emf of `C gt` emf of `D`
D. The negative terminal of `C` is connected to `A`

Answer

A

Explanation

(a) If e.m.f. of `c` is greater than the e.m.f. of the `'D'`
`I_(r) = 0`
So `r` does not play any role of zero deflection in galvanometer.