# What is magnetic potential energy?

1. Nov 28, 2012

### sudu.ghonge

We know that a Magnetic field does no work. Then how does an inductor store energy (1/2 LI2)? When that stored energy is needed, it can be retrieved back and clearly it can be used to do some work. In a fix here.

2. Nov 28, 2012

### cabraham

Who says a mag field does no work? Who? Mag fields store energy then transfer said energy to the form of electric, electromagnetic, thermal, kinetic, and/or chemical energy domain(s). Have you studied physics or EE extensively? Just curious why you make such sweeping generalizations such as a mag field doing no work, as if it were undisputed gospel? Nothing personal but what is the basis for saying mag fields do no work?

The only reason some give are the Lorentz force relations where mag force acts normal to a charge carrier's velocity. In this case the mag Lorentz force, Fm = quXB, is indeed not doing work on the charge carrier. But E & B fields are mutual & interdependent so that one of them, or both, can do work on dipoles, motors, etc. Also, if an inductor de-energizes into a passive network loop, the time varying B field includes an E field which does work on the charges. B transferred its energy to E which can do work on charges.

This is a topic which cannot be explained in a few posts. I will elaborate if needed.

Claude

3. Nov 30, 2012

### sudu.ghonge

Well, the Magnetic field still does no work. It is the induced electric field that does the work. Got this cleared from somewhere and partially from the second half of your answer.

This is a topic which CAN be explained in a single post. I will elaborate if needed.

4. Dec 3, 2012

### Khashishi

It's better to think of the magnetic field and electric field as part of the same thing: the electromagnetic field. Even if you want to make a distinction, the magnetic field still does work on charged particles through their magnetic dipole moments.