A particle of charge $Q$ and mass $m$ travels through a potential difference $V$ from rest. The final momentum of the particle is

A given charge situated at a distance $r$ from an electric dipole on it axis experiences a force $F$. If the distance of the charge from the dipole is doubled, the force acting on the charge will be

The adjoining diagram shows the electric lines of force emerging from a charged body. If the electric fields at $A$ and $B$ are $E_A$ and $E_B$ respectively and the distance between them is $r$, then

Capacity of an isolated sphere is increased $n$ times when it is enclosed by an earthed concentric sphere. The ratio of their radii is

A dipole having dipole moment $p$ is placed in front of a solid uncharged conducting  sphere are shown in the diagram. The net potential at point $A$ lying on the surface of the sphere is :-