An electric dipole of dipole moment is 6 . 0 × 10 ^ - 6 Cm placed...

The work done for rotating a dipole is given by the change in the potential energy. The potential energy is given by

$U = - \overset{\to}{p} \cdot \overset{\to}{E}$

$W = ∆ U = {U}_{f} - {U}_{i}$

So, the work done is

$W = - pEcos180 ° - ( - pEcos0 ° ) = 2pE = 2 \times 6 \times {10}^{- 6} \times 1 . 5 \times {10}^{3} = 18mJ$