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# Attraction/repulsion force between two equal magnets?

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## Attraction/repulsion force between two equal magnets?

(OP)
I have two magnets, each capable of attracting/repelling with 10N,
when they are attracted, is the force between them 20N? Since each magnet is applying a force?
Does it take 20N to attract them and 20 to split them apart?

I think the attraction force is greater than the repulsion force, I noticed it being a bit different and weaker.

### RE: Attraction/repulsion force between two equal magnets?

(OP)

It complicated to solve using this.
I'd probably take a guess and say based off the formula that both magnets are responsible for the force of attraction.

### RE: Attraction/repulsion force between two equal magnets?

(OP)
I'll look into it, but I think I'll kust experiment with multiple types of systems.

### RE: Attraction/repulsion force between two equal magnets?

Dear Vis99,

I'll cite an example to understand the force of the magnet. First, Let's have magnet with 1 mm away from a steel plate, the force of the magnet to the steel plate, say 10N. The steel plate have no remenant magnetism, so the magnet or the steel will move towards the other if you fix & lock one.

Now you replace the steel plate with the same identical magnet and if you see the force of attraction between two magnet will be 2x 10N i.e. 20 N

If N-pole of the magnet offers 10N of force, and the S-pole of the magnet will also offer 10N of force. Here all assumptions are based on simple axially magnetized magnet have 2 poles. If you see the separation of the poles in the magnet, the pole separation will be exactly placed at the centre perpendicular to the z-axis or the axis of magnetization.

Unless you change this pole separation line, or change the volume of the magnet, or the magnet having density gradient within the magnet, the force on the N&S pole will not change.

Similarly, if the force of attraction is 20N for 2 pole and the force of repulsion will also be 20N for 2 pole, unless you don't change any thing for an ideal magnet

Pl. let me know if any further queries

### RE: Attraction/repulsion force between two equal magnets?

ndsram
In terms of the force, its still 20N due to the 10N of each pole, with respect that all the properties are achieved(e.g pole separation line, volume, density gradient,)
What I have understood from what you said, is that the attraction/repulsion force will be 20N is a change in the attributes of the set-up the force could change.

### RE: Attraction/repulsion force between two equal magnets?

Yes the attraction force is the change in attribute which will directly influence the force. One of the main attribute is the distance between the two magnets.

Reg
N D Senthil Ram

### RE: Attraction/repulsion force between two equal magnets?

Yea, the gap is 0 in this case.
I just wanted to make sure it takes 10N from each magnet = 20N to attract them and 20N to split them apart.

### RE: Attraction/repulsion force between two equal magnets?

Can you please tell me your application
So I could give you some input on the same
Be assured that it ll take 20N of course no doubt, but have safety factor for consideration

### RE: Attraction/repulsion force between two equal magnets?

Refer to this book Permanent Magnet And Electromechanical Devices by Edward P. Furlani , chapter 4 pg 268 and above, you'll find good explanation for force and calculation

can you pl convert to mm and add the data

### RE: Attraction/repulsion force between two equal magnets?

max pulling force means the force between the magent and an infinite large steel plate with an infinite permeability, zero air gap. if this force is 10N, the force between two identical magnets will NOT be 20N except for at only one point where the Bd at the top of the two magnets is exactly doubled. at any other contditions, Bd does not double, and therefore the MAX pull force will not be doubled.
There is an upper limit to the pulling force where Bd=Br. For two infinite long magnets, the MAX pulling force is the same as for only one magnet.

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