Interactions between magnets(Exposition)

The behaviour of bar magnets

Take a simple bar magnet–the sort that is found in physics lessons–in the form of a rectangular block of steel. Bring another simple bar magnet towards it. The two magnets will either attract or repel each other. Turn one of the magnets around. If they repelled each other before, now they will attract.

It is clear that the two ends, or poles, of the magnets behave differently and there is a simple rule to describe their interaction:

  • identical poles (two north or two south) repel.
  • opposite poles (north and south) attract.
  • Put more concisely:

  • Like poles repel and unlike poles attract.
  • It is important to realise that here we are doing no more than saying what happens and making a simple rule. This is not an explanation of why there is attraction or repulsion. That explanation lies in the two magnets moving to reduce the energy stored between them but that is not a concern of the 11–14 curriculum!

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