magnet as a solenoid

[labview1958]

A permanent magnet can be model as a solenoid. If I have a permanent magnet of 1 Tesla, how much current is that equivalent to? My guess is about 1x10^5 Amps. Is that right?

[swansont]

It's about 8 x 10^5 amp/(turns/m) (the inverse of the magnetic permeability of free space, assuming no core). It depends on the density of the windings; you could get 1 Tesla with a much smaller current source

[labview1958]

Let's say the magnet is a cube of 1mm. Then the area of the north pole is 1mm x 1mm = 1 x10^-6.m^2. Is the total current on the north pole 8x10^5 x 1 x 10^-6 = 0.8 A ?

[labview1958]

Is it true that if a magnet is rated 1 Tesla, it should be considered as 1/3 Tesla for the attractive force between a steel plate placed on top and touching the magnet. Is it because there is always a small gap between the touching steel plate and magnet?

[swansont]

Let's say the magnet is a cube of 1mm. Then the area of the north pole is 1mm x 1mm = 1 x10^-6.m^2. Is the total current on the north pole 8x10^5 x 1 x 10^-6 = 0.8 A ?

 

 

The relevant equation is [math] B = \mu nI[/math] where n is the number of turns per unit length. If the core is air, then you use the permeability of free space