Question

The plot of the variation of potential difference across a combination of three identical cells in series, versus current is shown below. What is the emf and internal resistance of each cell ?

Answer 1

We know that,

V=E-Ir

Where E is the e.m.f and r is the total internal resistance.

When I=0,

Total emf=Terminal voltage

3E=6 V

or E=2 V

When V=0

E=Ir

$r=\frac{\text{Total E.m.f}}{I}=\frac{6}{1}=6\Omega$

As the cells are connected in series.So,the internal resistamce of each cell=$2\Omega$