Q18

A rectangular coil has dimensions $3.0\ \mathrm{cm}\times4.0\ \mathrm{cm}$ and carries a current of $15.0\ \mathrm{mA}$ in a uniform magnetic field of $3.0\ \mathrm{T}$. The coil has 20 turns of wire and is free to rotate about the axis as shown.

If the coil is rotated by $25^\circ$, what is the torque acting on the coil?
(A) $9.79\times10^{-4}\ \mathrm{N\,m}$ clockwise
(B) $9.79\times10^{-4}\ \mathrm{N\,m}$ anticlockwise
(C) $4.56\times10^{-4}\ \mathrm{N\,m}$ clockwise
(D) $4.56\times10^{-4}\ \mathrm{N\,m}$ anticlockwise