An electric dipole of moment \(\vec {p} \) is lying along a uniform electric field \(\vec{E}.\) The work done in rotating the dipole by \(90^{\circ}\) is:
1. \(\sqrt{2}pE\)
2. \(\dfrac{pE}{2}\)
3. \(2pE\)
4. \(pE\)
1. | stable in both \(A,B\) |
2. | stable in \(A\), unstable in \(B\) |
3. | unstable in \(A\), stable in \(B\) |
4. | unstable in both \(A,B\) |