Question

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

Answer 1

Given, $PD=v,current=I$

Since $V=E-ir\Rightarrow 0.4=E-0.04r\Rightarrow E=0.4+0.20r...1$

Similarly, $E=0.8+0.12R....2$

From equation 1 and 2 we get,

$0.4+0.20r=0.8+0.12r\Rightarrow 0.08r=0.4\Rightarrow r=40\Omega$

Now,

$E=0.4+0.20\times 5=0.4+1=1.4volt$