Naked Science Forum

On the Lighter Side => Science Experiments => Topic started by: CliffordK on 08/11/2012 19:54:59

Title: Is a needle shaped magnet stronger or weaker than a coin shaped magnet?
Post by: CliffordK on 08/11/2012 19:54:59
I was thinking of magnets with respect to another topic. (

Is a needle shaped (long skinny) magnet stronger or weaker than a coin shaped (short fat) magnet of equal mass?

One could run the experiment in a number of ways. 

You can purchase magnets that are magnetized through different faces.  So, for example if you had two identical sized bar magnets, one magnetized from end to end, and another magnetized side to side.  Then one could build an apparatus to test the lifting power of the magnet.  The weight in which the attachment to a steel plate breaks would be recorded.

Now, if one magnet is simply bigger than another, for example a cylinder bar magnet, 1 cm in diameter, cm long would be expected to be weaker than a bar magnet of identical material, 1 cm diameter,  2 cm long.

However, there are a couple of reasons to expect a difference for the two identical mass magnets.  The surface area at the attachment point would be smaller for the slender magnet, and the distance to the center of the magnet would also be longer for the slender one and shorter for the fat one.