# What makes the electrons move in conductor? (em induction)

1. Jan 7, 2008

### Physicsissuef

What makes the electrons move in conductor, while I am moving the magnet among the conductor in closed circular loop? It is the magnetic force from the magnet, but why when I get close the magnet they start moving in direction, oppose of the magnetic force?

2. Jan 7, 2008

### Staff: Mentor

What moves the electons is the induced electric field created by the moving magnetic field. The current is always induced in a direction to oppose any change in the magnetic flux through the loop. As you move the pole of a magnet towards the loop, you are increasing the flux in the loop--the electrons will move to reduce it.

See: http://hyperphysics.phy-astr.gsu.edu/hbase/electric/farlaw.html" [Broken]

Last edited by a moderator: May 3, 2017
3. Jan 8, 2008

### Physicsissuef

Why they want to reduce it?

Last edited by a moderator: May 3, 2017
4. Jan 8, 2008

5. Jan 8, 2008

### nanoWatt

This question made me think. Do only electrons produce an electric field, and what would the electric field be composed of? I am assuming the electric field is continuous with no gaps. I don't think it's solid electrons. I guess it's just some form of energy.

6. Jan 8, 2008

### ZapperZ

Staff Emeritus
Er.. this may be rather obvious, but protons do have charges too, you know.

And a changing magnetic field also produces electric field, per the Maxwell equations.

Zz.

7. Jan 8, 2008

### Physicsissuef

I read them, but still can't understand. Conservation of energy of the electrons or?

8. Jan 8, 2008

Doc Al?

9. Jan 8, 2008

### Staff: Mentor

It takes energy to get a current flowing. That energy comes from the work you have to do in pushing the magnet into the loop. (The induced current exerts a force on the magnet that opposes its motion--you have to push the magnet, which takes energy.)

10. Jan 8, 2008

### Physicsissuef

And when I push the magnet back, why the electrons are going in same direction of the magnetic field, so they want to connect with it?

11. Jan 8, 2008

### Staff: Mentor

The induced current always resists any change in flux. When you pull the magnet back you are acting to decrease the flux, so the current moves so as to increase it. (Again, this takes energy. You have to pull the magnet.)

12. Jan 8, 2008

### Physicsissuef

Ok, I understand that. But why it wants to increase it?