A solid conducting sphere of radius $10 \mathrm{cm}$ is enclosed by a thin metallic shell of radius $20 \mathrm{cm}$. A charge  $q=20 \mathrm{\mu C}$ is given to the inner sphere. Find the heat generated in the process when the inner sphere is connected to the shell by a conducting wire.

An electron travelling in a uniform electric field passes from a region of potential $V_1$ to a region of higher potential $V_2$. Then

Three concentric conducting spherical shells carry charges as follows: $+4Q$ on the inner shell, $-2Q$ on the middle shell and $-5Q$ on the outer shell. The charge on the inner surface of the outer shell is

A positive point charge $Q$ is kept (as shown in the figure) inside a neutral conducting shell whose centre is at $C$. An external uniform electric field $E$ is applied. Then,

Three concentric conducting spherical shells have radii $r, 2r$ and $3r$ and charges $q_1, q_2$ and $q_3$ respectively. Innermost and outermost shells are earthed as shown in figure. The charges shown are after earthing. Select the correct alternative.