A solid spherical conducting shell has inner radius a and outer radius $2a$. At the center of the shell is located a point charge $+Q$. What must the excess charge of the shell be in order for the charge density on the inner and outer surfaces of the shell to be exactly equal ?

 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

Explain electrostatics of conductors. Explain the effects produced inside a metallic conductor placed in an external electric field.

A conducting sphere of radius $r$ has a charge. Then

As shown in the figure, a point charge $Q$ is placed at the centre of conducting spherical shell of inner radius a and outer radius $b$. The electric field due to charge $Q$ in three different regions I, II and III is given by: $( I : r < a , II : a < r < b , III : r > b )$

A spherical conducting shell of inner radius $r_1$ and outer radius $r_2$ has a charge $Q. $

$(a)$ A charge $q$ is placed at the centre of the shell. What is the surface charge density on the inner and outer surfaces of the shell?

$(b)$ Is the electric field inside a cavity (with no charge) zero, even if the shell is not spherical, but has any irregular shape? Explain.