Question:
In the given circuit, an ideal voltmeter connected across the $10 \Omega$ resistance reads $2 \mathrm{~V}$. The internal resistance $\mathrm{r}$, of each cell is :
Correct Option: , 2
Solution:
(2) For the given circuit
$\mathrm{i}=\frac{3}{8+2 \mathrm{r}}$
Now voltage across $\mathrm{AB}$
$\mathrm{i} \times 6=\frac{3}{8+2 \mathrm{r}} \times 6=2$
$\Rightarrow 9=8+2 \mathrm{r}$
$\Rightarrow \mathrm{r}=\frac{1}{2} \Omega$