# How to calculate magnetic pole strength?

1. Oct 24, 2013

### abdo799

I have 2 magnets , i need to know the force between them , I searched a lot , conclusion was : we need to use a dipole-dipole interaction equation , which included m, which the magnetic dipole , i searched how to calculate it , and this is what i found . m=pl where p is magnetic pole strength and l is length of the magnet . I searched a lot on how to calculate p and found nothing.

2. Oct 24, 2013

### Simon Bridge

It's determined empirically.

3. Oct 25, 2013

### abdo799

It's so weird that no one tried to solve this , even the equation of the dipole-dipole interaction didn't exist before 1998

4. Oct 25, 2013

### Simon Bridge

Not really - we know, in principle, how to go about it ... it's just that there are too many variables for the solution to be practical.

The dipole strengths depend on all the magnetic domains inside the magnet - which depends on the geometry of the magnet, the material it is made out of, and how it was made. Do you know all those things about your magnets - at nanometer scales? Much easier just to measure it.

Note: the "effective dipole" approach is only an approximation.

5. Oct 25, 2013

### thegreenlaser

You'll find that a lot of "real world" physics problems are just too complicated to be worth solving by hand. We have to solve them either by experiment or using a computer simulation.