Question

It is observed in a potentiometer experiment that no current passes through the galvanometer when the terminals of the cell are connected across a certain length of the potentiometer wire. On shunting the cell by a 2 Ω resistance, the balancing length is reduced to half. The internal resistance of the cell is ______.

विकल्प

• 2 Ω

• 18 Ω

• 9 Ω

• 4 Ω

Answer 1

It is observed in a potentiometer experiment that no current passes through the galvanometer, when the terminals of the cell are connected across a certain length of the potentiometer wire. On shunting the cell by a 2 Ω resistance, the balancing length is reduced to half. The internal resistance of the cell is 2 Ω.

Explanation:

The internal resistance of the cell is given by:

r = `("I"_1/"I"_2 - 1) xx "R"`

r = `((2"I"_1)/"I"_1 - 1) xx "R"`

`=> "r" = (2 - 1) xx "R"`

r = R = 2Ω