Q148 / 160 · AP EAMCET 2021 (19 Aug Shift 2) · Physics

Charge on the outer sphere is $q$ and the inner sphere is grounded. The charge on the inner sphere is $q^{'}$ , for $(r_{2} > r_{1})$ . Then

Solution

Since the inner sphere is grounded, potential of the shell must be zero due to the charges on outer sphere and inner sphere.

$\Rightarrow \frac{k q'}{r_{1}} + \frac{k q}{r_{2}} = 0$

$\Rightarrow \frac{k q'}{r_{1}} = - \frac{k q}{r_{2}}$

$\Rightarrow q' = - \frac{r_{1}}{r_{2}} q$

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