An electric dipole with dipole moment \( 2\times10^{-8} \) C m is oriented at \( 30^\circ \) with respect to the direction of a uniform electric field of magnitude \( 5\times10^{4} \) N C\( ^{-1} \). The magnitude of the torque acting on the dipole is
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → \( 5\times10^{-4}\,\mathrm{N\,m} \)
A dipole in a uniform field experiences a torque \( \tau = pE\sin\theta \), where \( \theta \) is the angle between the dipole moment and the field.
\( p = 2\times10^{-8}\,\mathrm{C\,m} \)
\( E = 5\times10^{4}\,\mathrm{N\,C^{-1}} \)
\( \theta = 30^\circ \)
\( \tau = pE\sin\theta = (2\times10^{-8})(5\times10^{4})\sin 30^\circ \)
\( \tau = (10^{-3})(0.5) = 5\times10^{-4}\,\mathrm{N\,m} \)
Note: NTA picked this question from an NCERT (2026-27) exercise and changed the figures. Do not ignore NCERT while practising numericals.
NCERT (2026-27):
Exercises – …
