Permanent Magnets: Electromagnetic Wave Propagation?

[miloko]

Hi all,
I have this simple question that I never really understood. A permanent magnet generates a magnetic field around itself. Is there an electromagnetic wave propagation associated with this permanent magnet? If so, what is the frequency of the wave?

Thanks,
Mike

 

[pallidin]

Under current knowlege, the frequency is zero(it does not alternate with a permanent magnet) but the propagation of the magnetic field is at the speed of light.

 

[chroot]

The field is static and unchanging (magnetostatic) if the magnet is not moved. If you begin shaking it, then the field undergoes an oscillation with the frequency of the shaking.

- Warren

 

[HallsofIvy]

In other words, a "wave" occurs when the field changes. A regular change in a magnetic field causes a regularly changing electric field which produces a regularly changing magnetic field which produces ... (that's why the waves are called electromagnetic waves). With a permanent magnet, there is no changing field and so no wave.

 

[miloko]

Hi all,

In one of the books I'm reading, it says that shields are only used in the presence of alternating fields. However, in some websites, I see people using magnetic shields for permanent magnets which has a magnetostatic field. I ran some simulations, and the filed of a permanent magnet seems to be shielded by a layer of nickel. So, who's telling the truth?

Thanks,
Michael