- #1
Miyz
- 200
- 0
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
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!
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
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!
Last edited by a moderator: