How Do I Calculate Magnetic Force Against Distance?

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?
16:36 Wed 13th Jun 2007
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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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