Question
A proton has a magnetic field due to its spin on its axis. The field is similar to that created by a circular current loop $0.650 \times 10^{-15} \textrm{ m}$ in radius with a current of $1.05 \times 10^4 \textrm{ A}$ (no kidding). Find the maximum torque on a proton in a $2.50 \textrm{ T}$ field. (This is a significant torque on a small particle.)

$3.48 \times 10^{-26} \textrm{ N}\cdot\textrm{m}$

Solution Video