Question

What is the maximum current that can be drawn from a cell of emf $E$ and internal resistance $r$ connected to an external resistance $R$?

Answer 1

Step 1:Current drawn from a cell of emf $E$and internal resistance $r$ in an external resistance $R$ is given by:

$I=\frac{E}{R+r}$
Step 2: for maximum current, the external resistance $R$ should be zero i.e., for maximum current the terminals of a cell must be short circuited. Substitute $0$ for $R$ in the formula of current.

$I=\frac{E}{0+r}=\frac{E}{r}$

Hence, the Maximum current is $\frac{E}{r}$.