An electric dipole of moment P is placed along the direction of electric field E. The work done in deflecting the dipole through 180° is equal to

+2PE

The correct answer is Option (2) → +2PE

The work done in rotating an electric dipole in uniform electric field is,

$W=\int\limits_{θ_1}^{θ_2}τdθ$   [$τ$ = Torque]

and,

$τ=PE\sin θ$   [P = Dipole moment]

$⇒W=\int\limits_{θ_1}^{θ_2}PE\sin θdθ$

$=\int\limits_{0°}^{180°}PE\sin θdθ=PE\left[-\cos θ\right]_{0°}^{180°}$

$=2PE$