A magnet is any object that generates its own magnetic force, called a magnetic field. Despite being invisible, a magnet’s magnetic field is responsible for producing the force that attracts other objects.
The ancient Greeks discovered that some rocks, known as lodestones, produced their own magnetic field. Today magnets are specially made.
Magnets come in many shapes and sizes and can be made from different types of material but only metals are magnetic.
How do magnets work?
Magnets can attract other materials. Only metals are attracted to magnets but not all metals are. Every magnet ever made has two poles - a north and a south pole. Magnets produce lines of magnetic force which leave a magnet from its north pole and re-enters the magnet at the south pole.
When two magnets are placed together one magnet’s north pole will attract the other’s south pole. However, two north poles or two south poles will always repel each other.
Which materials are magnetic?
Some magnets are stronger than others. You can test two different types of magnets by seeing which one will hold more paperclips. Of course, not all materials are magnetic; use the activity sheet below and a bar magnet to identify which materials are magnetic and which ones aren't.
Did you know the Earth actually produces its own magnetic field? This is because Earth’s core is mainly made up of iron, one of the best materials for making magnets. Part of the Earth’s core is continuously spinning really really fast, which creates a magnetic field and is the reason why the Earth has a North Pole and a South Pole. This is really helpful for explorers and adventurers as they can use a compass to find out which way is north and which way is south.
What is a compass?
A compass is made of a tiny magnet in the shape of a needle which is allowed to spin. Because the north pole of a compass’ magnet will always point towards the Earth’s North Pole they are really important for helping people find their way. Use the activity below to create your own compass in three easy steps.
A magnet's magnetic field exists within the space immediately around the magnet, it’s here where a magnets magnetic force is strongest. The further you are from the magnet, the weaker the magnetic field is. Permanent magnets continually produce their own magnetic field but normally you can't see it. Use the activity sheet below to find out how to do a fun experiment using iron filings and various magnets to see their magnetic fields.
There are two main types of magnets, permanent magnets and electromagnets.
Permanent magnets never lose their magnetism, they are the typical round, bar or horseshoe shaped magnets that you will have seen before. They are made by heating up magnetic material such as iron to really high temperatures and then cooling it in the presence of a really strong magnetic field. This makes some of tiny the particles, known as magnetic domains, within the magnet face the same way. The material is then magnetised by placing it within another strong magnetic field which magnetises all the tiny particles that are already facing the same way. Each tiny particle now exerts its own magnetic field! You can magnetise everyday items such as a needle by rubbing it in the same direction with a bar magnet. Try it for yourself!
Electromagnets are created using electricity and a magnetic material such as iron, an iron nail is perfect for this example. When electricity passes through a copper wire it creates a magnetic field around the wire. By winding a coil of wire around an iron core you can increase the strength of the magnetic field produced and create an electromagnet. Unlike permanent magnets, an electromagnets magnetism can be turned off by removing the electricity or battery. Make your own electromagnet using the activity sheet below.
The poles of a magnet are the points at which a magnet’s magnetic field is strongest, usually either end of a magnet. Lines of magnetic force exit a magnet from its north pole and enter through its south pole finding the easiest route. That’s why, if you chop a magnet in two, you get two new separate magnets, each with a north and a south pole.
Relationship between magnets and electricity
We've seen how the flow of electricity can create a magnetic field. Similarly the movement of a magnet can generate electricity if a wire is placed within the magnetic field in such a way that it cuts through a magnets magnetic lines of force. You really can’t have electricity without magnetism and vice versa. The relationship is known as electromagnetism.
AGE 14-16 YEARS
What are electrons and why do they make magnets stick?
An electrical current moving along a wire creates its own magnetic field. It is these moving electrical charges that are also responsible for a permanent magnet’s magnetic field, more specifically, it is the movement of tiny charged particles called electrons that creates a magnetic field.
An electron is a negatively charged particle found in all atoms, they are found in every atom and are continually moving. While they don’t move very far, the movement is enough to create a small magnetic field.
Generally, electrons move in pairs and in each pair one electron spins in one direction and the other spins in the opposite direction. Because each spins in a different direction, the magnetic fields created by each cancel each other out.
However, materials that we call ferromagnetic, e.g. magnetic materials like iron have several unpaired electrons that are all spinning in the same direction, each creating a magnetic moment and therefore make a material magnetic.
The materials that make good magnets are the same as the materials magnets attract. This is because magnets attract materials that have unpaired electrons that spin in the same direction. In other words, the property that turns a metal into a magnet also attracts metal to magnets.
What is a ferrous metal?
It is rare that metals are used in their raw form, they are often mixed with other metals and elements with different properties to make an alloy. The word ferrous is used to describe a material that contains a lot of iron. Therefore, it means that these materials are commonly magnetic.
History of electricity and magnetism
Take a trip through history with this timeline of electricity and magnetism!
Without magnets, thousands of everyday items that we have come to take for granted would never have been possible and we don’t just mean the magnets on your fridge! Without magnets there would be no electric motors, no loudspeakers, no smartphones, fewer medical advancements, no wind turbines and you wouldn’t be reading these words on screen as there would be no computer hard drives. You really do owe a lot to magnets! Can you identify the objects in the activity sheet below, the clue is they all contain magnets!