A current loop of magnetic moment m is placed in a uniform field B so that m makes angle θ with B. The torque on the loop has magnitude:

1. The torque on a magnetic dipole is $\boldsymbol{\tau} = \mathbf{m}\times\mathbf{B}$. 2. The magnitude of a cross product is $\tau = mB\sin\theta$. 3. Here $\theta$ is the angle between m and B. 4. The torque is maximum at $\theta = 90^\circ$ and zero at $\theta = 0$, ruling out the cos θ form. _Source: syllabus Physics Ch 4 "Moving Charges and Magnetism", p.156_