Question

In the given figure, battery E is balanced on 55 cm length of potentiometer wire but when a resistance of 10 `Omega` is connected in parallel with the battery, then it balances on 50 cm length of the potentiometer wire. The internal resistance r of the battery is ____________.

Options

• `1  Omega`

• `3  Omega`

• `10  Omega`

• `5  Omega`

Answer 1

In the given figure, battery E is balanced on 55 cm length of potentiometer wire but when a resistance of 10 `Omega` is connected in parallel with the battery, then it balances on 50 cm length of the potentiometer wire. The internal resistance r of the battery is `1  Omega`.

Explanation:

`"r" = ((l_1 - l_2)/l_2) xx "R'"`

`therefore "r" = ((55 - 50)/50) xx 10`

`= 1  Omega`