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Re: [Phys-l] solenoidal and cylindrical EM sourced magnetic fields.

On 6/10/2011 11:38 AM, Bernard Cleyet wrote:
On 2011, Jun 10, , at 07:11, Moses Fayngold wrote:

So a solid coil, i.e. not a solenoid has the same field?
As far as we are interested in the FAR field (its dependence on distance), it
is the same for all three objects - a circular coil, a solenoid, or a
cylindrical magnet.


My solid coil is many (to fill space) solenoids inside each other (co-axial) does this make a difference?


bc again not clear.

It washes out in the far field. For fun, I took data from the calculator you used, of the force of attraction of a 1X1 inch cylindrical D42 magnet to a steel plate over 5 doublings of range.
I set an equation finder (Eureqa) to solving for least mean error, least max error etc., and it would not fit an inverse square or cube law, pure and simple. Same for repulsion.

Brian W