# Effect of the magnetic field on a charged object's inertia.

1. Dec 13, 2011

### Envergure

A question many of us repeatedly solved in high school goes like this: An electron is accellerated a certain distance by an electric field of a certain strength. Determine its final velocity.

I and my teachers always treated this as a simple F=ma question, but recently it's occurred to me that a moving charge has a magnetic field, and magnetic fields store energy. Does that mean the electron would end up moving more slowly because some of the energy that goes into the electron goes into the magnetic field? Does this mean the electron has an "inertia" mass higher than its "gravity charge" mass?

2. Dec 13, 2011

### Simon Bridge

You are saying that some of the energy that may otherwise have gone into the motion of the charge gets stored in it's magnetic field?

This does not change the inertia of the object though, just it's kinetic energy.
Have a go working out how big the effect is.

3. Dec 13, 2011

### Drakkith

Staff Emeritus
I don't believe that magnetic field of a single particle can store energy. I think you are referring to the effect of induction, which is different.

4. Dec 13, 2011

### Simon Bridge

5. Dec 13, 2011

### Nabeshin

6. Dec 13, 2011

### Simon Bridge

Of course in the semi-classical model of transport in a semiconductor, an electron is treated as having an effective mass different from it's rest mass.

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