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Here's an applied physics question. ;) If I buy some cube or sphere magnets like these, can I aggregate them together to create a stronger magnet (almost as strong as a single magnet)?

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Although the combined strength will be larger, it will not be exactly the same as the strength of single large magnet. This is because the magnets lower down in the stack are being shielded slightly by the magnets above and below them.

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So the magnetic material at the center of a single magnet will not be affected the same way the magnets in the center of an equally sized magnet cluster will be? –  Matt Chambers Dec 12 '11 at 22:40
    
@MattChambers The fact that there is a finite gap between any two magnets in a stack means you are introducing a distance from a magnet which otherwise would not be there. Magnetic fields, from a dipole, drop off as the cube of the distance so even small distances can end up playing a role. –  Omar Dec 13 '11 at 0:23
    
It was tough to decide which answer to accept. Thanks to all of you. I went with Omar because he came back to respond to my question. –  Matt Chambers Dec 13 '11 at 18:27
    
@MattChambers Thanks :-) –  Omar Dec 13 '11 at 18:32
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To expand on Omar's Answer: KJMagnetics has an FAQ that answers this question: http://www.kjmagnetics.com/FAQ.asp#stack. If you wander round the KJMagnetics site, they give a lot of technical information (I bought some magnets off them 2-3 years ago).

Their FAQ answer describes the situation for stacking flat magnets vertically on top of each other. Note that if you place multiple magnets next to each other horizontally, instead of in a vertical stack, they will still act in the same way as a larger magnet having the same area. However, in the horizontal case, the magnets will repel each other because like poles are next to each other (N next to N, S next to S). So you would have to impose an equal and opposite force to keep them together. That's not easy when the magnets get large.

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I don't understand your comment. I missed googling for the FAQ answer since I was using "aggregate" instead of "stack." What's the difference between "stakc" and "next to each other"? Don't North and South poles attract? –  Matt Chambers Dec 12 '11 at 23:10
    
@Matt: I submitted an edit to hopefully try to clarify. –  Mark Beadles Dec 13 '11 at 1:08
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