Question

For a cell the graph between the potential difference (V) across the terminals of the cells and the current drawn from the cell is as shown in the figure. calculate the emf and the internal resistance of the cell.

Answer 1

Given,

Potential difference $=v$

Since $v=E-ir$

$0.4=E-0.04r$

$E=0.4+0.04r....1$

Similarly,

$E=0.8+0.204r....2$

From equation 1 and 2, we get,

$0.4+0.04r=0.8+0.204r$

$r=f\Omega$

Now, the Emf $E=0.4+0.20\times 5$

$0.4+1=1.4volt$