Question

In a potentiometer experiment, the balancing with a cell is at length $240cm$. On shunting the cell with a resistance of $2\Omega$ , the balancing length becomes $120cm$. The internal resistance of the cell is

• A. 1$\Omega$
• B. 0.5$\Omega$
• C. 4$\Omega$
• D. 2$\Omega$

Answer 1

Answer: (D)

2$\Omega$

Internal resistance of a cell $r$ is given by

$r=R[\frac{l_1}{l_2}-1]$
$\Rightarrow r=2[\frac{240}{120}-1]$
$\Rightarrow r=2\times 1=2\Omega$