$A$ thin metallic spherical shell contains a charge $Q$ on it. $A$ point charge $+q$ is placed at the centre of the shell and another charge $q'$ is placed outside it as shown in the figure. All the three charges are positive. The force on the central charge due to the shell is:

$A$ charge of $Q$ coulomb is placed on a solid piece of metal of irregular shape. The charge will distribute itself:

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

Assertion $:-$ The maximum charge that can be given to a conductor of fixed volume depends on its shape.
Reason $:-$ If the electric field near the conductor is sufficient for dielectric breakdown of air,no more charge can be transferred to it.

Consider an initially neutral hollow conducting spherical shell with inner radius $r$ and outer radius $2r$. $A$ point charge $+Q$ is now placed inside the shell at a distance $r/2$ from the centre. The shell is then grounded by connecting the outer surface to the earth. $P$ is an external point at a distance $2r$ from the point charge $+Q$ on the line passing through the centre and the point charge $+Q$ as shown in the figure. The magnitude of the force on a test charge $+q$ placed at $P$ will be

Which of the following statements is $NOT$ true for a charged conducting sphere?