Magnetic fields

 

What is a magnetic field?

A permanent magnet has magnetism no matter what its shape is. It has two ends that are different from each other. These ends are called poles. One pole is north (N) and the other pole is south (S).

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.

 

 

The magnetic field of a magnet is shown by lines with arrows that point from North to South.

 

The north and south poles have the strongest magnetic fields, which you can see by how many lines there are.

The magnetic field strength depends on how far apart the lines are.

 

• The magnetic field is stronger when the lines are closer together – this happens at the poles.
• The magnetic field is weaker when the lines are further apart – this happens as you move away from the poles.

 

Magnetic interactions

Magnetic materials are always attracted towards a magnet. However, a magnet may be attracted to or repelled from another magnet.

 

 

Opposite poles

We can use the magnetic field lines of two magnets to show how opposite poles attract.

 

 

In the example above, you can see 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.

 

Like poles

We can also use the magnetic field lines of two magnets to show how like poles repel.

 

 

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 is why, when like poles are positioned near each other, they repel each other.

 

Summary:

 

• A permanent magnet always has magnetism. It has a magnetic field that we cannot see.
• Only some materials, like iron, can feel a magnetic force.
• A magnetic force can make things attract or repel each other.