A short bar magnet of magnetic dipole moment \( 10^{-5}\,\mathrm{A\,m^{2}} \) is kept in a uniform magnetic field \( 3\times10^{-4}\,\mathrm{T} \) at an angle of 30°. The torque acting on it is:
Answer & explanation
Correct answer: option 1
The correct answer is Option (1) → \( 1.5\times10^{-9}\,\mathrm{N\,m} \)
The torque on a magnetic dipole of moment m in a uniform field B is \( \tau = mB\sin\theta \), where \( \theta \) is the angle between m and B.
\( \tau = 10^{-5}\times3\times10^{-4}\times\sin30^\circ = 3\times10^{-9}\times\frac{1}{2} = 1.5\times10^{-9}\,\mathrm{N\,m} \)