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
Answer & explanation
Correct answer: option 2
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]
$⇒W=\int\limits_{θ_1}^{θ_2}PE\sin θdθ$
$=\int\limits_{0°}^{180°}PE\sin θdθ=PE\left[-\cos θ\right]_{0°}^{180°}$
$=2PE$