Chronology Current Month Current Thread Current Date
[Year List] [Month List (current year)] [Date Index] [Thread Index] [Thread Prev] [Thread Next] [Date Prev] [Date Next]

Re: [Phys-L] breaking magnets




On 2014, May 04, , at 13:51, John Denker <jsd@av8n.com> wrote:

On 05/04/2014 01:28 PM, Ken Caviness asked:
is the force at any given distance provided by the combination of 2
disc magnets on some object = twice the force of one disc magnet at
the same distance on the same object? Or is it greater/less than
twice the force of one disc magnet? My quick and dirty model says
"=", but "slightly greater" wouldn't surprise me.

That's ill posed!

The "force at any given distance" is not simply a function of
distance; it depends on angle.

In particular, there will be some points where the field due
to the two-disk stack is zero, even though the field due to
either disk separately would be nonzero. This happens near
the equator of the two-disk stack.

Hint: Model each disk as a simple current loop.
_______________________________________


uses current loop:

Field Calculator for Off-Axis Fields Due to a Current Loop

http://www.netdenizen.com/emagnet/offaxis/iloopcalculator.htm


the formulae:

Off-Axis Field of a Current Loop


http://www.netdenizen.com/emagnettest/offaxis/?offaxisloop


PMs: Not the one I used)



Magnetic Field Calculators and Magnet Calculations - Magnet Solutions from Dexter Magnetic Technologies

http://www.dextermag.com/resource-center/magnetic-field-calculators



experiment:



The Magnetic Field of a Permanent Magnet > Experiment #31 from Physics with Vernier > Vernier Software & Technology

http://www.vernier.com/experiments/pwv/31/magnetic_field_of_a_permanent_magnet/

bc required for variable g (magnetic simulation) of a pendulum