# What causes electric field/ magnetic field?

## Homework Statement

What causes electric field? What causes magnetic field?
(I) stationary electric fields
(II) moving electric charges
(III) a changing magnetic field
IV) a current-carrying wire

E=F/q
B=μI/2πr
E electric field
F elecric force
Q charge
B magnetic field
I current

## The Attempt at a Solution

[/B]
I) Stationary electric charges creates electric fields tht points radially outward/inward.
II) moving electric charges, like current flowing through a wire, cause magnetic fields. Can it produce electric fields as well since it is a charge?
III) That statement has me confused. It’s a change in magnetic field, so current is induced. It’s Faraday’s law. But what is caused exactly? Any hints?
IV) same as II

DrClaude
Mentor
II) moving electric charges, like current flowing through a wire, cause magnetic fields. Can it produce electric fields as well since it is a charge?
Yes, the electric field is there whether the charge is moving or not.

III) That statement has me confused. It’s a change in magnetic field, so current is induced. It’s Faraday’s law. But what is caused exactly? Any hints?
A current can only be induced if there is a conductor. Faraday's law is one of the Maxwell equations, so you can check what they look like in free space.

IV) same as II
Review this question with respect to what I wrote for II.

Then, a moving chrage causes both electric and magnetic fields.
I have check maxwells equations, and yes, it can create electric fields.
Current carrying wire creates only magnetic field. Am I right?

DrClaude
Mentor
Then, a moving chrage causes both electric and magnetic fields.
I have check maxwells equations, and yes, it can create electric fields.
Current carrying wire creates only magnetic field. Am I right?
Yes, because the net charge is zero (the wire itself is neutral).

YMMMA