Question

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

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

Answer 1

Answer: (D)

$2\,\Omega$

Answer 2

Internal resistance of a cell is R $\quad\left(\frac{\ell_{1}-\ell_{2}}{\ell_{2}}\right)=2 \left(\frac{240-120}{120}\right)=2 \Omega$