Answer to Question #300920 in Electricity and Magnetism for aisme

Question

A rectangular current-carrying wire loop which is free to rotate about a vertical axis in a uniform magnetic field of 1.42 T is rotating anti-clockwise. The current in the loop is 250 mA. The distance between a to b is 20 cm.

Determine the magnetic force exerted on a-b.

Answer 1

$F=4IBl\cos 45°=200~mN.$