Q124 / 160 · WBJEE 2009 · Physics

Two identical cells each of emf $\mathrm{E}$ and internal resistance $\mathrm{r}$ are connected in parallel with an external resistance $\mathrm{R}$. To get maximum power developed across $R$, the value of $R$ is

  • Correct answer
    A
    $R=r / 2$
  • B
    $\mathrm{R}=\mathrm{r}$
  • C
    $R=r / 3$
  • D
    $\mathrm{R}=2 \mathrm{r}$

Solution

$R_{e q}=\frac{r}{2}$ $I=\frac{2 E}{r+2 R}$ For max. power consumption. I should be max. So denominator should be min. for that $r+2 R=(\sqrt{r}, \quad)$

Hence, the correct answer is option: 'A'.

Relevant Questions