An electric dipole is placed parallel to the electric field. Let...

The work done in rotating an electric dipole in a uniform electric field from an initial angle $\theta_1$ to a final angle $\theta_2$ is given by $W = pE(\cos\theta_1 - \cos\theta_2)$.

Initially, the dipole is parallel to the electric field, so \theta_1 = 0^{}^{\circ}.

The work done in rotating the dipole by 60^{}^{\circ} is:

W = pE(\cos 0^{}^{\circ} - \cos 60^{}^{\circ})

$W = pE(1 - 0.5) = 0.5 pE$

$\Rightarrow pE = 2W$

The dipole is further rotated by 120^{}^{\circ}, making the final angle with the electric field \theta_2 = 60^{}^{\circ} + 120^{}^{\circ} = 180^{}^{\circ}.

The total work done from the initial position is:

W_{\text{total}} = pE(\cos 0^{}^{\circ} - \cos 180^{}^{\circ})

$W_{\text{total}} = pE(1 - (-1)) = 2pE$

Substituting $pE = 2W$:

$W_{\text{total}} = 2(2W) = 4W$

Answer: $4\text{W}$