What is magnetism?
Playing with magnets is one of the first bits of science most children discover. That’s because magnets are easy to use, safe, and fun. They’re also quite surprising. Remember when you first discovered that two magnets could snap together and stick like glue? Remember the force when you held two magnets close and felt them either attract (pull toward one another) or repel (push away)? One of the most amazing things about magnets is the way they can attract other magnets (or other magnetic materials) “at a distance,” invisibly, through what we call a magnetic field.
To ancient people, magnetism must have seemed like magic. Thousands of years down the line, we understand what happens inside magnetic materials, how their atomic structure causes their magnetic properties, and how electricity and magnetism are really just two sides of the same coin: electromagnetism. Once scientists would have said magnetism was the strange, invisible force of attraction between certain materials; today, we’re more likely to define it as a force created by electric currents (themselves caused by moving electrons).
What is a magnet?
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 others 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 that planet Earth is a big magnet?
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.
SIX things to know about magnets
- A magnet has two ends called poles, one of which is called a north pole or north-seeking pole, while the other is called a south pole or south-seeking pole.
- The north pole of one magnet attracts the south pole of a second magnet, while the north pole of one magnet repels the other magnet’s north pole. So we have the common saying: like poles repel, unlike poles attract.
- A magnet creates an invisible area of magnetism all around it called a magnetic field.
- The north pole of a magnet points roughly toward Earth’s north pole and vice-versa. That’s because Earth itself contains magnetic materials and behaves like a gigantic magnet.
- If you cut a bar magnet in half, it’s a bit like cutting an earthworm in half! You get two brand new, smaller magnets, each with its own north and south pole. (This is, of course, a joke. You don’t get two worms if you cut a worm in half. But you do get two magnets.)
- If you run a magnet a few times over an unmagnetized piece of a magnetic material (such as an iron nail), you can convert it into a magnet as well. This is called magnetization.
Magnets & Magnetic Fields
Magnets are used all over the world in almost all modern devices from computer hard drives to the latest environmentally friendly cars and transportation. With so much information available on the internet we have provided a basic introductory guide to magnets & magnetic fields. A Magnet is a material which produces an invisible magnetic field which can attract ferromagnetic materials. Magnets can also attract or repel other Magnets. All Magnets have at least 2 magnetic poles.
What materials can be attracted to a magnet?
Materials containing Iron, (steel contains iron) Cobalt and Nickel are ferromagnetic and are attracted to a magnet. Most other materials such as wood, plastic, aluminum and copper are not attracted to a magnet and are called non-magnetic.
What are Poles?
Every Magnet has at least two magnetic poles, one NORTH and one SOUTH and a magnetic field flows continuously from NORTH to SOUTH. A North pole has the same attracting force as a South pole when attracting Ferromagnetic materials.
Repelling and attracting
If two bar magnets are pushed together end to end, then they will either attract each other or repel each other depending on which polarities are used (North to South, North to North or South to South) Like Poles repel – Two North poles will repel each other (push each other away). Two South poles will also repel each other. Opposite Poles attract – A North pole will attract a South pole (jump towards and stick to each other)
Magnetic Fields
A magnetic field flows from North to South and if you place a piece of paper on top of a magnet and sprinkle fine iron powder on top, the shape of the invisible magnetic fields become visible as the fine iron powder clings to them. There are many shapes of magnet and each has a different magnetic field shape.
- Bar magnets maintain a constant magnetic pull.
- Electromagnets can be turned on or off (this is what makes them so useful in creating simple motors).
- Opposite magnetic poles attract and similar magnetic poles repel each other.
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