Question

A cell of internal resistance $r$ is connected to an external resistance $R$. The current will be maximum in $R,$ if

• A. $R=r$
• B. $R<r$
• C. $R>r$
• D. $R=\frac{r}{2}$

Answer 1

Answer: (A)

$R=r$

In series combination of cells, Current $I=\frac{nE}{nr+R^{\prime }}$

In parallel combination of cells, $I^{\prime }=\frac{E}{\left(r/n\right)+R}$

If $I=I^{\prime }$ then $\frac{nE}{nr+R}=\frac{E}{\left(r/n\right)+R}=\frac{nE}{r+nR}$

It will be so if $r=R$.