A hollow conducting sphere of inner radius $R$ and outer radius $2R$ is given charge $Q$ as shown in the figure, then the

A charged particle having a positive charge $q$ approaches a grounded metallic spheres of radius $R$ with a constant small speed $v$ as shown in figure. In this situation,.

There is a fixed positive charge $Q$ at $O$, and $A$ and $B$ are points equidistant from $O$. A positive charge $+q$ is taken slowly by an external agent from $A$ to $B$ along the line $AC$ and then along the line $CB$.

$S$ is a solid neutral conducting sphere. A point charge $q$ of $1\times {10}^{-6} \mathrm{C}$ is placed at a point $A$. $C$ is the centre of the sphere, and $AB$ is a tangent. $BC=3 \mathrm{m}$ and $AB=4 \mathrm{m}$,