An electric dipole is placed in uniform electric field in an unstable equilibrium position. Now the dipole is rotated in this field. The graph which best represents variation of its potential energy is given by,

Three charges of $+2q$, $-q$ and $-q$ are placed at the corners $A$, $B$ and $C$ of an equilateral triangle of side $a$, as shown in the adjoining figure. Then the dipole moment of this combination is

A dipole of dipole moment $\overrightarrow{p}=(2\hat{\mathrm{i}}-3\hat{\mathrm{j}}+4\hat{\mathrm{k}}) \mathrm{cm}$ is kept at a point $A$ whose coordinates are $(1,-1,3)$. If an external electric field $\overrightarrow{E}=(5\hat{\mathrm{i}}+2\hat{\mathrm{j}}-3\hat{\mathrm{k}}) \mathrm{V} {\mathrm{m}}^{-1}$ is applied then the potential energy of the dipole be,

An electric dipole is placed in a uniform electric field $\overrightarrow{E}$ of magnitude $40 \mathrm{N} {\mathrm{C}}^{-1}$. The graph below shows the magnitude of the torque on the dipole versus the angle $\mathrm{\theta }$ between the field $\overrightarrow{E}$ and the dipole moment $\overrightarrow{p}$. The magnitude of dipole moment $\overrightarrow{p}$ is equal to