`AB` is a potentiometer wire of length `100 cm` and its resistance is `10 ohms`. It is connected in series with a resistance `R = 10 ohms` and a battery of e.m.f. `2 V` and negligible internal resistance. If a source of unknown e.m.f. `E` is balanced by `40 cm` length of the potentiometer wire, the value of `E` is

Options

A. `0.8 V`
B. `1.6 V`
C. `0.08 V`
D. `0.16 V`

Answer

D

Explanation

(d) `E = (e)/((R + R_(h) = r)) (R )/(L) xx l`
`= (2)/((10 + 40 + 0)) xx (10)/(1) xx 0.4 = 0.16 V`