Question

In a circuit a cell with internal resistance r is connected to an external resistance R. The condition for the maximum current that drawn from the cell is?

• A. R $=$ r
• B. R $<$ r
• C. R $>$ r
• D. R $=0$

Answer 1

The correct option is A R $=$ r

The maximum current drawn from the cell will be in the case when the external resistance is minimum.

The current in the circuit will be given by:

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

So, the smallest value of denominator will give maximum current.

Therefore, for maximum current, the value of $R$ should be equal to zero.

Option, $\left(D\right)$ is correct.