# I Electric, magnetic fields and induced currents

1. Jun 26, 2016

### Wston

Hi,

I've been trying to figure several simple things about electric and magnetic fields, their relationship with current.

From what I've read these were presented as natural laws:
1. Changing magnetic field induces current in a conductor, causes electrons to move in other words.
2. Changing magnetic field creates changing electric field.
3. Changing electric field creates changing magnetic field.

Got several questions. One question is, does changing magnetic field induce current (move electrons) by first creating changing electric field ? I am trying to figure out if there are 2 or 3 steps in the process.

(1)Changing magnetic field -> (2)changing electric field -> (3)moving electrons
or is it
(1)Changing magnetic field -> (2)moving electrons ?

I can think of first option with 3 steps (changing magnetic field->electric field->current) as electric field exerting forces on charges (electrons), hence their movement. On the other hand if there are only 2 steps (changing magnetic field->current), how does that work...because for charges to move there must be an electric field, what causes charges to move otherwise ? individual magnetic fields of electrons ?

2. Jun 26, 2016

### Staff: Mentor

1 is correct, but 2 and 3 are not entirely correct. A changing magnetic field can produce either a static or dynamic (changing) magnetic field. If the rate of change of the magnetic field is constant, then the electric field produced is constant. Otherwise the electric field created is not constant. The same is true for a changing electric field. The induced magnetic field can be either static or dynamic.

I'm not certain. I've only gone through a basic E&M class, so I don't have the knowledge to answer this. I think the changing magnetic field induces an electric field, which then exerts a force on the charged particles, but like I said I'm not certain.

3. Jun 27, 2016

### Wston

Thanks a lot for the answer, that's an interesting detail I misunderstood about changing fields producing constant one if the rate of change is constant.