## Coulomb's Law/Universal Gravitation for Magnets

Hey, everyone, I'm new here. I signed up to get an equation that I would really like to find, but I've been searching for a few days and haven't found anything that helped. What I'm wondering is how to find the force between two magnets. Once I have that equation, I'll ask another one that I want to combine with it. Thanks for help from anyone out there willing to stick out a helping hand!

Mentor
 Quote by DFTBA Hey, everyone, I'm new here. I signed up to get an equation that I would really like to find, but I've been searching for a few days and haven't found anything that helped. What I'm wondering is how to find the force between two magnets. Once I have that equation, I'll ask another one that I want to combine with it. Thanks for help from anyone out there willing to stick out a helping hand!
I googled Force Between Two Magnets, and got lots of helpful hits. You could try the same search to see if it gives you what you need. Here is one of the hits for a force calculator:

http://www.kjmagnetics.com/calculator.asp

BTW, your thread title is worrisome. What in the world do you mean by it?
 My first thought was that he wants something like this, F = qv x B DFTBA, is this familiar?

## Coulomb's Law/Universal Gravitation for Magnets

 Quote by berkeman I googled Force Between Two Magnets, and got lots of helpful hits. You could try the same search to see if it gives you what you need. Here is one of the hits for a force calculator: http://www.kjmagnetics.com/calculator.asp BTW, your thread title is worrisome. What in the world do you mean by it?
I mean that there is an equation for attraction between charges: Coulomb's law. There is an equation for attraction between masses: universal gravitation. I'm asking for the same idea, but with magnets.

That equation is not familiar to me. Most of my research does not involve magnetism. However, I don't understand how that could work. Stationary magnets still attract, but the equation seems to say a zero velocity would yield a non-existent force.
 The 'v' is the velocity of the charge 'q'. Magnets are complicated collections of lots of charges. The equation is a vector equation with the 'x' being a cross product. Note that when you combine it with the coulomb force you get the "lorentz force", F= qE + qv x B http://en.wikipedia.org/wiki/Lorentz_force http://hyperphysics.phy-astr.gsu.edu...ic/magfor.html
 Okay, this seems to be on the right track. But how do I put two magnets into the equation?
 That is a lot more complicated. Magnets are bulk materials made up of many particles that have charge and "magnetic moments" (link). The properties are fundamentally quantum mechanical and quite complex. I think your best bet is to start with the links I gave you for understanding the basic theory behind the magnetic force. I would use the link provided by berkeman to find the force of a real physical magnet. (or an experiment of your own) This is one area where it take a lot of work to go from the basic theory to a real prediction.

 Quote by DFTBA Okay, this seems to be on the right track. But how do I put two magnets into the equation?
I believe that one is looking for the mathematics describing dipole-dipole interactions.

Some simple geometries: http://en.wikipedia.org/wiki/Force_b...magnetic_force

It becomes more complex with the goemeteries of the sources of the magnetic fields.
http://en.wikipedia.org/wiki/Magneti...le_interaction