Two spheres of radius $R$ and $2R$ having charge $Q$ and $2Q$ respectively are placed far away from each other. How much charge will flow when key $k$ is pressed?

What is earthing or grounding in household electrical circuits?

An empty thick conducting shell of inner radius $a$ and outer radius $b$ is shown in the figure. If it is observed that the inner face of the shell carries a uniform charge density $-\sigma$ and the outer surface carries a uniform charge density $\sigma'$,if the outer surface of the shell is earthed,then identify the correct statement$(s)$.

'Inside a conductor,the electrostatic field is zero'. Explain.

Two uniformly charged spherical conductors $A$ and $B$ of radii $5 \ mm$ and $10 \ mm$ are separated by a distance of $2 \ cm$. If the spheres are connected by a conducting wire,then in equilibrium condition,the ratio of the magnitudes of the electric fields at the surface of the sphere $A$ and $B$ will be.

Assertion: $A$ metallic shield in the form of a hollow shell may be built to block an electric field.
Reason: In a hollow spherical shield,the electric field inside it is zero at every point.