measuring magnets in repulsion force

[labview1958]

Let's say I have two pairs of identical magnets. The first pair is 1 Tesla. The second pair is 2 Tesla. If I have unlike poles facing each other as below, would the total force on the balance be the same?

 

1T2T

 

1T2T

Balance

 

0r

 

1T2T

 

2T1T

Balance

[[Tycho?]]

I'm not sure what you are asking here. I can't visualize your problem, could you try to rephrase it?

[labview1958]

Sorry. It's like poles facing each other. The bottom pair is placed on a weighing machine. The upper pair is held up by a retort stand etc. Let's all have north poles face each other.

 

First Kes.

1 Tesla faces 1 Tesla

2 Tesla faces 2 Tesla.

 

Second kes.

1 Tesla faces 2 Tesla

2 Tesla faces 1 Tesla.

 

Would the weighing machine register the same force?

[Meir Achuz]

No. The force would be greater in the first case.

When a strong magnet faces a weaker magnet, N to N, the stronger magnet tends to demagnetize the weaker magnet. A strong N opposite a weak enough N can even attract.

[Meir Achuz]

Even if there were no demagnetization of the weaker magnet, the ratio of forces would be 5/4.

[LazerFazer]

How would you calculate the force of repulsion between the two magnets?

 

LF

[labview1958]

What about the diagonal repulsion. Is that taken into account? What if I rotate a smaller like pole over a much larger like pole. Would the weighing machine register a constant or a variable force, assuming the weighing machine is accurate to 0.0001g?

[Meir Achuz]

How would you calculate the force of repulsion between the two magnets?

 

LF

Most texts don't do this.

In order to push two bar magnets together would take a force

F=2\pi MM'A, where M and M' are the magnet strengths in gauss, A the area in cm^2, and F is in dynes.

Actually, the force would be somewhat less than this due to the demagnetization, which depends on the actual material of the magnets.