Around a magnet, there are invisible magnetic field lines that indicate the magnetic field.
These magnetic field lines always come out of the north pole and go towards the south pole. This is shown by the direction of the arrows.
Make sure to include arrowheads, as they indicate the direction of the field lines. The magnetic fields are strongest at the north and south poles, which is shown by the line concentration.
The distances between the field lines show how strong the magnetic field is.
Two ways that magnetic field lines can be shown are:
Using plotting compasses is one way to visualise magnetic field lines.
Here we have many small compasses surrounding the bar magnet. As you can see, the north pole is pointing towards the south pole at all times. If you extend the lines, they will start to resemble the original magnetic field diagram, extending from the north pole and leading to the south pole.
Another way to show magnetic field lines is by placing a bar magnet in a pile of iron filings. The iron fillings will sort themselves along the magnetic field lines.
Here we can see the iron fillings showing the magnetic field around the bar magnet.
We can use the magnetic field lines of two magnets to show how opposite poles attract.
In this scenario, you can observe the field lines of the two magnets interacting. As we know that field lines travel from north to south, it is easy to see why there is an attraction between opposite poles.
Now let’s look at like poles. For example, two north poles placed next to each other.
As the magnetic field lines are trying to go from north to south, the magnets will repel each other. The magnetic field lines of the magnets are not touching because the magnetic field lines are trying to reach the south pole.
This means that when like poles are positioned near each other, they repel each other.