For an infinite line of charge having charge density $\lambda$ lying along $x$-axis, the work required in moving charge $q$ from $C$ to $A$ along arc $CA$ is:

 

Two short electric dipoles are placed as shown ($r$ is the distance between their centre). The energy of electric interaction between these dipoles will be

($C$ is centre of dipole of moment $P_2$)

A charge $q$ is placed at the centre of the cubical vessel (with one face open) as shown in the figure. The flux of the electric field through the surface of the vessel is

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