An interesting question to pose would be the following: what would the world be like if we didn’t have electromagnets?
Whilst magnets themselves – and the magnetic field in general – are naturally occurring phenomena, electromagnets really aren’t. They had to be invented. And, given that these things combine an electric current with a magnetic material, they arrived in our lives actually relatively late in the history of things.
Electromagnets are some of the most powerful magnets we have. And, because of this, they have become absolutely crucial to industry, technology, and all sorts of different everyday things that we have about our homes.
And so, learning about electromagnets is not just wild, irrelevant theory, no. Rather, they are hugely useful – and can do things that only they can actually do. Not to mention the fact that the science of the electromagnet is pretty fascinating in itself.
So back to that question: where would we be these days without the power of the electromagnet? The answer, honestly, is nowhere very much at all. We’d have no generators – and no possibility of power storage and power transmission – for example.
But we’ll come back to that question later. Let’s take a little look at the theory of the electromagnet.
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When Did We Discover the Electromagnet?
Without the electromagnet, the chances are that we’d still be living in something a bit like the 1820s.
This technology wasn’t invented until the 1820s, when two separate scientists – one in Denmark, and the other, William Sturgeon, in England – began playing with the interaction of electricity and magnetism. It was Hans Christian Ørsted (or Oersted) who first realised that an electrical current creates a magnetic field, whilst Sturgeon made the first, rudimentary, electromagnet.
However, no-one knew quite how this coil of copper wire could produce a magnetic field for another century, almost, when in 1906 a French physicist started to tackle the problem. And with his theory of the magnetic domain, we came a step closer to knowing what on earth was actually happening in the middle of all that coiled wire.
But this story misses two of the most important names in the history of electromagnetism. You might have heard of Michael Faraday – who discovered the principle of electromagnetic induction. Or of André-Marie Ampère, who showed that two parallel wires repel and attract each other depending on which way the current passes – and who gave his name to the amp (or ampere).
Electromagnetism has, since then, been a technology that has gone from strength to strength, filling our world with things that we don’t even realise have such an importance.
Let’s take a look at the science.
Recap: What is Magnetism?
The science of electromagnetism is based on the object of the magnet and all its related phenomena: the magnetic poles, magnetic force, and the charged particles which animate all this at a subatomic level.
But do you remember what magnetism is precisely? We discuss it in detail in our article, What is Magnetism?, yet it is helpful to have a little recap here.
Magnetism works because of unpaired electrons. Whilst electrons are the particles that make up part of the atom, most materials have electron pairs with opposite charges. These charges are known as ‘spins’ and are conventionally known as ‘positive charge’ and ‘negative’.
When electrons are paired, their respective magnetic moment is neutralised – meaning they have no magnetic force.
However, when they are unpaired, they are not neutralised – and in properly magnetic materials, scientifically known as ferromagnetic materials, these electrons can all spontaneously point in the same direction, giving the material properly magnetic properties.
This ferromagnetism is found in materials like iron and nickel.
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What is Electromagnetism?
Whilst this is the way that magnetism works ‘naturally’, electromagnets work slightly differently. The discoveries of the likes of Ampère, Faraday, and Ørsted lay in precisely the realisation that this wasn’t the only way in which magnetism worked.
Rather, they saw that electrical current flow also has a magnetic field. Ampère’s discovery – that wires with currents flowing in opposite directions attract each other – proved this.
In electromagnetism, the whole of the wire through which the electricity is flowing becomes magnetized. This, again, is due to the electrons. But rather than just directed in a certain way – or arranged ‘inline’ – in an electric current the electrons are untethered from their atoms and flow along the length of the material. This provides the magnetic strength.
However, electromagnetism – this combination of magnetism and electricity – is quite a lot more important than just the electromagnet itself.
In fact, electromagnetism is actually described as one of the fundamental interactions that motivates all physical laws (the others being gravitation, weak, and strong interactions). And so electromagnetism is actually the force that keeps atoms together, it is responsible for light, and it is responsible for the bonding of chemical compounds.
It is really a very busy thing, electromagnetism. And its discovery – as well as our ability to harness its power – has been a hugely important part of human’s scientific development.
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How Do Electromagnets Work?
But how do these things work, these electromagnets precisely? We’ve heard enough about the background, but how does an electromagnet per se function.
An electromagnet works in pretty much the same way as a simple bar magnet. It has, like such a normal permanent magnet, a north pole and a south pole, which tend to reject the identical poles of other magnets. Again, in the same way, it produces a magnetic field – the same that you would be able to see with iron filings.
However, the difference between an electromagnet and a normal one is that an electromagnet has a much stronger magnetic field. And, of course, you can turn it off and on by switching off the current. Both of these things make it particularly useful.
The Structure of an Electromagnet.
As we discussed above, the physical reason for the magnetic force differs between a normal ferromagnet and its electromagnetic cousin. In the former, the electrons are aligned – yet, in the latter, the current of electrons that is electricity produces the magnetic field.
So, wires themselves are magnetic, as Ampère showed. But to make an electromagnet, we use a more sophisticated method.
This method is based on coils of wire. Take a cylindrical piece of ferromagnetic metal such as iron and wrap the wire coiling – usually made of copper – around it. As soon as you switch the electricity on, the current will run through the wire and will magnetize the metal in the centre – just like a permanent magnet.
Switch the electricity off and the metal will cease to be magnetic.
It’s that simple really. And you don’t strictly need the iron core – as the magnetic field that coil produces is already centred on the hole through the middle of the coil. However, that iron core, or ‘magnetic core’, makes the electromagnet even more powerful – thousands of times more powerful.
You could make an electromagnet yourself, if you wanted to. But be careful – and do it under supervision.
What Do We Use Electromagnets for?
So, let’s return to that question, what would the world be like these days if we didn’t have electromagnets? It really is a fascinating question – and we could perhaps phrase it better as what things wouldn’t we have if we didn’t have electromagnets?
The answer is potentially quite long. But we can answer this question with reference to some of the most powerful and ubiquitous technologies that use electromagnetism. They are honestly everywhere.
Electric Motors and Generators.
An electric motor – that you’ll find in cars and all sorts of other machines – relies on the interaction of a magnetic field with an electrical current.
These are made from a stator – a magnet around the edge of the motor that remains static – and a rotor, a rotating electromagnet that is almost identical to the coil described above.
As electricity is put into the coil, the coil becomes attracted to the stator, which is then flipped so that it repels it. Consequently, the coil continually spins and produces mechanical energy.
These, motors, by the way, are in everything from your computer to your headphones, your oven to your hard drive.
Generators are identical, mechanically; they just work in the opposite direction.
Given that electrical power lines carry hundreds of thousands of electrical volts, before that electricity enters your toaster (which only needs some two hundred volts), it needs to be reduced in voltage. That’s what a transformer does.
It works through the placement of two coils. That huge electrical voltage passes through the first coil. If you put a coil with fewer turns in it alongside it, the electrical current will jump across to the next coil – but will have a lower voltage.
Without this thing, you wouldn’t be able to use any electrical equipment in your house.
One of the coolest things people have done with electromagnets is magnetic levitation, or maglev. This is a transport system in which trains levitate – and can go faster more efficiently due to the lack of friction.
This requires to sets of very strong magnets. One lifts the train from the rails and the other propels it done the track.