Question

${}^{\prime }{n}^{\prime }$ cells, each of emf ${}^{\prime }{e}^{\prime }$ and internal resistance ${}^{\prime }{r}^{\prime }$ are joined in series to form a row. ${}^{\prime }{m}^{\prime }$ such rows are connected in parallel to form a battery of $N=mn$ cells. This battery is connected to an external resistance ${}^{\prime }{R}^{\prime }$
What is the emf of this battery and how much is its internal resistance?

Answer 1

$emf=ne$

Internal resistance of $1row=nr$

$\frac{1}{r^{\prime }}=\frac{1}{nr}+\frac{1}{nr}+.....mtimes$

$\frac{1}{r^{\prime }}=\frac{m}{nr}$

$r^{\prime }=\frac{nr}{m}$