- All magnets have a north pole and a south pole (N and S).
- The magnetic force acts between magnets. It works as follows:
- Opposite poles attract
- Like poles repel
All magnets have a north pole and a south pole. These are labelled as N and S:
The simplest example of a magnet is a bar magnet; a rectangular bar with the two poles at opposite ends. We can think of other magnets as bar magnets that have been stretched into a different shape.
The force between two magnets depends on which way their poles are facing:
- Opposite poles attract:
- Like poles (i.e. poles with the same sign) repel:
(NB: The arrows indicate the direction of the magnetic force acting on each magnet)
Notice how this is quite similar to the electric force!
The magnetic force might still feel a bit mysterious — how does each magnet ‘know’ that the other magnet is there? Find out how on the next page...
Want to win a Nobel Prize? Here's how:
Find a magnet that only has one pole.
No one has ever found one, and most theories assume they don't exist. But maybe they do!
How will you know if you've found one? You have found a magnetic monopole if it only ever attracts one pole of a (normal) magnet, regardless of which orientation you hold the monopole magnet.
A very good question! You might imagine that if you cut a magnet in half, then you'll be able to separate the North and South poles, like this:
Let's try it for real, and see what happens:
Surprise! It turned into two smaller bar magnets!
This is surprising because we have though of the north and south poles as ends of a magnet. But it's better to think of a magnet as lots of arrows, where the end with the arrow tips is the N end, the end with the arrow tails is the S end.
When a magnet is cut in half, we're really just cutting these arrows in half. Since the arrows still face the same way, each smaller magnet will have North on the right, and South on the left.