I'm just confused... I know that magnetic fields can do work only on pure magnetic dipoles like a bar magnet. Based on the formula, the magnetic force on a charge is qv⃗ ×B⃗ which is identically perpendicular to v⃗ and that's why it does no work. However, forces on magnetic dipoles and more general objects don't have the form v⃗ × - they're not perpendicular to v⃗ , so they do work in general. But still when I look at this picture I get confused: http://ecommunity.pwsd76.ab.ca/file.php/1030/moddata/resource/23766/physics_30/images/m4/103_dc_motor.jpg [Broken] In this picture aren't magnetic force causing the rotation of the loop! Aren't the magnetic forces in a motor on of the key! Factors of motion within it? I mean it makes no sense to me why in this cause magnetic force can't do work on an electric charge... Could someone pelase help me out with this!