Magnetic force and distance

[Shinecat]

Hi all!

I am working on another permanent magnetic motor geometry.
In the past month i complete a geometry. At the moment i don?t know it is possible to work, or not.
But have a question:

What is the mathematical connection between the magnetic force strenght and distance?
What is the simple / simlified formula which symbolize this connection?

Other words?
Take two magnets and put them near together with the same poles. The magnets are repulsing themselves.

When the distance is increasing in linear way, the magnetic force strenght decreasing linear?
Or exponential? Or how?

So, what is the formula of decreasing?

I think it is an important question, if anyone want to create working and useful designs.
Thanks everyone, who answer me, and sorry for my wrong english.

[gyulasun]

Hi,

I quote from a page:

<<Elementary physics states that the magnetic field of a magnetic dipole is approximately proportional to the inverse cube of the distance from the dipole. Therefore, if you double the distance from the magnet, the magnetic field strength will be reduced (roughly) by a factor of 8. >>

I think there are further interesting details on your question here:

http://www.exo.net/~pauld/activities/magnetism/forcebetweenmagnets.html    and also here:

http://van.hep.uiuc.edu/van/qa/section/Electricity_and_Magnets/Magnets/20050220232939.htm

Good experimenting.

rgds

Gyula

[Shinecat]

Thank you Gyula! Good pages. 

[ken_nyus]

This will help me too, thanks to the poster!

[Honk]

This link will show how the force of a magnet will weaken by distance.
http://www.imstrading.com/cgi-bin/flux-graphs.pl
You must register for free to be able to use it.

And here's a calculation on a 2x2x1" N50 magnet I made.