Assertion: No two electric lines of force can intersect each other.

Reason: Tangent at any point of electric line of force gives the direction of electric field.

An electric dipole of dipole moment $\overrightarrow{p}$ is oriented parallel to a uniform electric field $\overrightarrow{E}$, as shown. It is rotated to one of the four orientations shown below. Rank the final orientations according to the change in the potential energy of the dipole-field system, most negative to most positive.

A dipole of dipole moment $\overrightarrow{p}=2\hat{\mathrm{i}}-3\hat{\mathrm{j}}+4\hat{\mathrm{k}}$ is placed at the point $A(2, -3, 1)$. The electric potential due to this dipole at the point $B(4, -1, 0)$ is equal to (All the parameters specified here are in $\mathrm{SI}$ units.),

In the figure the net torque acting on the dipole is