# Homework Help: Electric field by a current carrying wire

1. Feb 15, 2012

### jaobyccdee

Aside from magnetic field, Does a wire carrying current induce also an electric field? If yes, what rule should i use to find its direction?

2. Feb 15, 2012

### Dick

Does a wire carrying a current have a net electric charge? What do you think?

3. Feb 15, 2012

### jaobyccdee

Yes, so negative charges go one way, and positive charges go another direction. Isn't it?

4. Feb 15, 2012

### Dick

The picture is usually that negative charges (the electrons) go one way and the positive charges (the atoms that have lost an electron) are fixed in a metal. But there's no reason to assume there are more of one than the other. If there is a net charge then you can't compute it from the current. No, there is no electric field that you can figure out from just knowing the current.

5. Feb 15, 2012

### jaobyccdee

1. If there are the same number of positive charge and negative charge, then there's no net charge, and thus no electric field?
2. Can i say since a constant current has a magnetic field that doesn't change, so an electric field is not induced?
3. If the number of positive charge and negative charge are not the same, there is a net charge, then is there an electric field?
4. does a static current same as a constant current?

Thanks a lot!

6. Feb 16, 2012

### Dick

1. That's what Gauss' law would say. 2. A constant current creates a constant magnetic field - but that's not why the electric field is zero. 3. If the wire has a net charge, there will be an electric field. 4. I don't know what "static current" means - the only way I can think of the interpret it is "constant current".