When two cells of equal emf and equal internal resistance are connected in series the current is sam

Question

When two cells of equal emf and equal internal resistance are connected in series the current is same as when they are connected in parallel with the same  external resistance being 1 ohm. The internal resistance is\

Professor PC Thomas Classes · Answer

$I_{1}=\frac{2 E}{2 r+1}$\ \ $I_{2}=\frac{E}{\frac{r}{2}+1}$\ given that $\mathrm{I}_{1}=\mathrm{I}_{2}$ 
$ \frac{2 E}{2 r+1}=\frac{E}{\frac{r}{2}+1} $
 $2\left(\frac{\mathrm{r}}{2}+1ight)=2 \mathrm{r}+1$\ $\mathrm{r}=1 \Omega$