A positive point charge $q$ is placed at a distance $2 R$ from the surface of a metallic shell of radius $R$. The electric field at centre of shell due to induced charge has magnitude
Zero
$\frac{1}{4 \pi \varepsilon_0} \frac{q}{9 R^2}$
$\frac{1}{4 \pi \varepsilon_0} \frac{q}{4 R^2}$
$\frac{1}{4 \pi \varepsilon_0} \frac{q}{R^2}$
Aspherical shell with an inner radius $'a'$ and an outer radius $'b' $ is made of conducting material. A point charge $+Q$ is placed at the centre of the spherical shell and a total charge $- q $ is placed on the shell.
Charge $- q $ is distributed on the surfaces as
The electric field near a conducting surface having a uniform surface charge density $\sigma $ is given by
Figure shows a solid conducting sphere of radius $1 m$, enclosed by a metallic shell of radius $3 \,m$ such that their centres coincide. If outer shell is given a charge of $6 \,\mu C$ and inner sphere is earthed, find magnitude charge on the surface of inner shell is ............. $\mu C$
Two concentric spherical shells of radius $R_1$ and $R_2$ have $q_1$ and $q_2$ charge respectively as shown in figure. How much charge will flow through key $k$ when it is closed
A non uniformly shaped conductor is charged then at it's sharpest point