Three identical metal plates with large surface areas are kept parallel to each other as shown in the figure. The leftmost plate $A$ is given a charge $Q$ and the rightmost plate $C$ is given a charge $-2Q$. The middle plate $B$ is neutral. Then the charge appearing on the outer surface $S$ of the plate $C$ is:

If on two concentric hollow spheres of radii $r$ and $R$ $(R > r)$,the total charge $Q$ is distributed such that their surface charge densities are equal,then the potential at their common centre is:

$A$ point charge $q = 1 \mu C$ is located at a distance $2 \text{ cm}$ from one end of a thin insulating wire of length $L = 10 \text{ cm}$ having a charge $Q = 24 \mu C$,distributed uniformly along its length,as shown in the figure. The force between $q$ and the wire is . . . . . . $N$. (Use $\frac{1}{4 \pi \epsilon_0} = 9 \times 10^9 \text{ N} \cdot \text{m}^2 / \text{C}^2$)

$A$ solid sphere of radius $R_1$ and volume charge density $\rho = \frac{\rho_0}{r}$ is enclosed by a hollow sphere of radius $R_2$ with negative surface charge density $\sigma$, such that the total charge in the system is zero. $\rho_0$ is a positive constant and $r$ is the distance from the centre of the sphere. The ratio $R_2/R_1$ is

How much charge should be placed on a spherical shell of radius $25 \ cm$ to have a surface charge density of $\frac{3}{\pi} \mu C/m^2$ (in $\mu C$)?

Write an equation for the electric potential due to a linear charge distribution.