Question

The e.m.f of a cell is 2.0 volt and the internal resistance is 0.1 ohm.It is connected with a resistance of 3.9 ohm.Then potential difference across the cell is

• A. 0.20 V
• B. 1.90 V
• C. 1.95 V
• D. 2.00 V

Answer 1

The correct option is C 1.95 V

$r$ is the internal resistance.

$R$ is the external resistance.

$\epsilon$ is the emf of the cell.

Using Kirchoff's voltage law, $-2+I(r+R)=0$

$I=\frac{2}{4}=0.5A$

Potential difference across the cell,$V=\epsilon -Ir=2-0.05=1.95V$