# How Do I Calculate Magnetic Force Against Distance?

brassmonkey | 17:36 Wed 13th Jun 2007 | Science
I'm trying to work out the attraction between two magnets at varying distances apart. I know that it takes 750g of weight to break them apart when touching, but I cannot find a formula to predict how much is required if they are 1mm apart, 2mm apart etc.

I have found some articles which say that magnetic force obeys the inverse square law, but this can't be used when I don't know where the poles are within the magnets. If I assume the poles are in the faces of the two magnets, then the inverse square law predicts a magnetic force of infinity if the two poles are touching!

Can anyone help?

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No best answer has yet been selected by brassmonkey. Once a best answer has been selected, it will be shown here.

The most obvious and simple way to simplify the problem is to assume the poles are in the middle of each magnet.
I suppose you tried it already? How did it go?
do it old skool - Do a quick experiment, bung the results into excel (proper old skool I know!) or use a pen, then interpolate / extrapolate to your hearts content!

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