# Homework Help: Electromagnetic induction

1. Jun 11, 2010

### thereddevils

How is magnetic flux different from magnetic field? Or rather how are they related to each other ?

My thought is say there is a magnetic field acting along the x-axis direction, a conductor is allowed to fall through the magnectic field and now there is a change in magnetic field, hence magnetic flux is produced ?

Is is sth like that?

And also whats eddy current? Is it the current induced when there is a change in magnetic flux and eddy current is simply the special name for it ?

2. Jun 11, 2010

### AndyK

Induction?Flux?Field?or Eddy currents? Although they are all related they have different definitions. You basically said, I do not understand this whole sources of magnetic fields chapter can someone explain it to me...

Flux is like flow, electromagnetic field flow. In order to have flux( any flux) you need a surface and something to penetrate it. In this case EM field lines are penetrating some arbitrary surface. In order to create an emf using electromagnetism, you need to create a change in flux. This can be achieved by varying the surface that the field lines going thru, or varying the field lines themselves. This of course happens with respect to time, so you either have a time varying magnetic field or a time varying area. Emf is calculated by taking negative time derivative of the dot product of the magnetic field vector and the normal to the surface that they are penetrating.

Specify what you are looking for and I am sure more people with chime in.

3. Jun 11, 2010

### Daft

A magnetic field is any region where a magnetic force is obtained

Magnetic flux is a measure of how much magnetic force is obtained in a particular area

Does that help?

4. Jul 28, 2010

### navy_hamy

OK. I have no idea whether is this related to electromagnetic induction or anything else?! I have been trying to figure it out for some time and I cant.
A uniform magnetic field B is perpendicular to the plane of a circular loop of diameter 0.10m formed from wire of diameter 0.0025m and a resistivity 1.69x10^-8. At what rate must the magnitude of B change to induce a 10A current in the loop?

5. Jul 28, 2010

### navy_hamy

OK. I have no idea whether is this related to electromagnetic induction or anything else?! I have been trying to figure it out for some time and I cant.
A uniform magnetic field B is perpendicular to the plane of a circular loop of diameter 0.10m formed from wire of diameter 0.0025m and a resistivity 1.69x10^-8. At what rate must the magnitude of B change to induce a 10A current in the loop?