Question

For a cell of emf 2 v, a balance is obtained for $50cm$ of the potentiometer wire. if the cell is shunted by a $2\Omega$ resistor and the balance is obtained across $40cm$ of the wire, thye internal resistance of the cell is

• A. $0.25\Omega$
• B. $0.50\Omega$
• C. $0.80\Omega$
• D. $1.00\Omega$

Answer 1

The correct option is B $0.50\Omega$

$r=\left\{(l_1-l_2)/l_2\right\}\times R$

$l_1=50cm$

$l_2=40cm$

$R=2\Omega$

$r=\frac{50-40}{40}\times 2$

$r=0.50$