The invention of the electromagnet has had a profound effect on the way that we live our lives – though most of us don’t know it.These devices come in a myriad of different shapes and sizes, and they’ve made a myriad of technologies possible.Electromagnetism is one of the universe’s fundamental forces, and is responsible for everything from light to electricity.
Let’s take a look at some of the places you’ll find an electromagnet today – starting with one of the most common.
In order to get an internal combustion engine going, it’s necessary to first ‘turn’ it, allowing air to flow into the cylinders and ignite the fuel inside.In order to do this, modern cars, vans and trucks use an electric motor known as the starter motor, which draws power from a battery which is in turn charged by alternators.These devices require a great deal of current to get going, and so having them activated manually by a switch would cause an unpleasant amount of arcing.Inside an engine, a spark of this sort could be very dangerous, and so it’s necessary to use an electromagnet to pull the two contacts together extremely quickly.Though a spark might still occur, it won’t have the time necessary to heat the surrounding air to the point that fumes can ignite.This design is fairly common, with BMW, Ford, Audi, Mercedes and Vauxhall starter motors all operating via broadly similar principles.
A Magnetic Resonance Imaging scanner, or MRI scanner, is able to provide an accurate image of the interior of a human body (among other things) without the need for an invasive procedure.It’s revolutionised modern medicine, and allowed potentially life-threatening conditions to be identified and addressed far more swiftly and decisively.
Your body is made principally from water, which is in turn built from hydrogen and oxygen atoms.With an atomic weight of just one, each hydrogen atom contains a single positively charged proton, which acts like a small magnet. When your body is subject to a magnetic field, these protons will be pulled in the same direction.When the magnetic field is turned off, they’ll emit a burst of radio signal, which will be interpreted by the part of the MRI scanner responsible for the actual imaging.
These massive instruments that are being used to delve the deepest mysteries of the universe are actually comprised of a myriad of large electromagnets.These devices are used to propel single particles through an enormous loop, until they approach somewhere close to the speed of light.
One device you’re never far from in the modern world is the loudspeaker.Whether it’s the tiny speaker on your mobile phone or the massive ones you’ll find at your local cinema or music venue, speakers are excellent for providing audio which wouldn’t otherwise be practical.
Loudspeakers work by tethering an electromagnet to the rear of a cone.When electronic signal is passed through the electromagnet, the cone is drawn backwards and forwards, resulting in changes in air pressure which we hear as sound.A microphone works in broadly the same way, except in reverse – airborne vibrations are turned into electrical current based on how far an electromagnet is from the ribbon that’s being moved by a voice (or drum, or other sound-source).
Induction hobs work by turning an electromagnet to the bottom of a magnetically-active pan.Rather than moving the pan across the hob, however, the magnets move the individual particles of the pan so quickly that heat is generated, allowing you to cook.The key advantage of an induction hob is that it doesn’t generate any heat unless there’s a pan placed on it – making it far safer than more traditional varieties of hob.
Magnetic levitation trains work by suspending the carriages above a magnetic track, which allows the carriage to hang in mid-air, and propels it to its destination.Maglev trains are exceptionally expensive, and so are rare, but they also allow trains to go incredibly quickly, with very little friction.The lift-to-drag ratio of a good maglev system can exceed that of an aircraft, making it among the most efficient modes of transport (though the air-density at ground level is significantly higher than that found at altitude, ensuring that planes aren’t in danger of being replaced just yet.They also hold advantages over conventional trains; they’re faster, more durable, cheaper to run and they don’t need to worry about snow piling up on the track beneath them!