Question

A circular loop of radius a, carrying a current i, is placed in a two - dimensional magnetic field. the centre of the loop coincides with the centre of the field (figure 34 - E4). The strength of the magnetic field at the periphery of the loop is B. Find the magnetic force on the wire.

Answer 1

Required force

$F=\int dF={\int }_0^{2\pi a}idlB$

$=2\pi aiB$ perpendicular to the plane.