Q 12-02-005NEETNEET 2025Top questionEasy
An electric dipole with dipole moment $5 \times 10^{-6}$ C m is aligned with the direction of a uniform electric field of magnitude $4 \times 10^5$ N/C. The dipole is then rotated through an angle of $60°$ with respect to the electric field. The change in the potential energy of the dipole is :
Answer: (B) $1.0$ J
$U = -pE\cos\theta$, so
$$\Delta U = pE(\cos 0° - \cos 60°) = 5 \times 10^{-6} \times 4 \times 10^5 \times \left(1 - \frac{1}{2}\right) = 2 \times 0.5 = 1.0\ \text{J}$$
Solution by Sreeraj P, M.Sc Physics