`AB` is a potentiometer wire of length `100 cm` and its resistance is `10 ohms`. It is connected
Channel: Doubtnut
Date: 2020-01-19

`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