Practicing Success

Target Exam

CUET

Subject

Physics

Chapter

Electrostatic Potential and Capacitance

Question:

There are two concentric metal shells of radii r1 and r(>r1). If the outer shell has a charge q and the inner shell is grounded, the charge on the inner shell is

Options:

zero

−(r1/r2)q

r1r2q

Correct Answer:

−(r1/r2)q

Explanation:

Let the charge on inner shell be Q.

Since it is grounded, the potential of the shell must be zero due to both charge on inner shell and that on outer.
$ V = \frac{kQ}{r_1} + \frac{kq}{r_2} = 0$
$\Rightarrow Q = -q \frac{r_2}{r_1}$