# I Electric field of electric current

1. Oct 3, 2016

### hokhani

Does electric current also produces electric field (in addition to magnetic field) at a typical stationary point? In other words, electric current includes the moving charges. Do these charges produce electric field at a stationary point? Or, does the electric field of these charges come into the form of the magnetic field observed at this point?

2. Oct 3, 2016

### Simon Bridge

All charges produce an electric field.
The magnetic field is the effect of an electric field due to moving charges.
You've seen the special relativity explanation of magnetism?

3. Oct 6, 2016

### hokhani

Thanks. I haven't seen the special relativity explanation of magnetism. Do you mean that one who is moving with charge, sees the electric field of charges at the stationary point while one who is resting at the stationary point, sees that field as a magnetic field?

4. Oct 7, 2016

### Simon Bridge

That's the idea ... but since there is no such thing as a "stationary point", we have to say an observer who is stationary wrt the wire carrying a current see's the B field of the current while the one stationary wrt the current sees just an electrostatic field. Electricity and magnetism are "unified" into one electromagnetic force, with the everyday separate-seeming effects actually being mixed up together like time and space is in relativity - it's the effect of perspective.
The more complete description is that both effects are the result of an underlying phenomenon we call "electromagnetism". The whole thing is even simpler in the particle physics model. Where is your education up to right now?

5. Oct 7, 2016

### hokhani

I am PhD student of solid state physics and I haven't been involved in some fundamental concepts.

6. Oct 7, 2016

### Simon Bridge

Oh neat - we share a field, though I have not practised for some time. Electromagnetism is fundamental to solid state, but you have more quantum theory than relativity.

You would normally cover the unification of electricity and magnetism in year 1 undergraduate work (In NZ anyways)... but the SR description may not be covered until year 2. Looks like you just need a primer ... a quickie is to find the lecture series where the subject is covered and ask the lecturer for the notes (and/or sit-in on the lectures). There's a bunch of different ways to catch up depending on where your maths is: it may be worthwhile to start with covarient formulism of Maxwell's equations and GR in flat spacetime than go back to undergrad step-by-step. OR just think in terms of field theory.