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Magnets, and in particular electromagnets, are incredible devices which have shaped the technological world to a degree that few of us really appreciate. You’ll find them in an enormous amount of different places, both inside and outside the home. Let’s take a look at ten devices that have transformed the human experience, but which simply wouldn’t be possible without the help of magnetism.
As recently as the middle of last century, there were just a few magnets in the average home. Today, that figure has risen incredible – you’ll now find hundreds of them, doing big jobs and small ones.
Let’s start our list off with the most obvious sort of magnet – the ones which actually include the word magnet in their name. These little devices are, in comparison to the other members of this list, quite superficial. They serve as miniature decorations and souvenirs, and provide a way of temporarily attaching a shopping list to the fridge door.
Magnetic Resonance Imagining provides a non-intrusive way of peering into the internal organs of a patient and diagnosing ailments far sooner than would otherwise be possible. They work by bombarding the body with radio waves. Water molecules react differently to this stimulus that the other molecules of the body, and thus it’s possible to use magnets to interpret these differences and describe them as an image of the interior.
While solid-state drives of the sort that are being increasingly rolled out into modern computers don’t use any moving parts, this technology’s predecessor was a disk-based system which stored information magnetically onto several platters. A magnet would be used to position the read-head, spin the disks, and store the information. Without this particular innovation, computers as we know them today simply wouldn’t have been possible.
Kinetic power stations like hydroelectric dams, wind turbines and tidal power stations translate the motion of an external body into electrical energy. They do this through what’s called magnetic induction – by moving a fixed magnet near to (or within) coils of wire, they can induce a current in the latter.
Of course, this principle can also work in reverse, as in the starter motor of your car. This device isn’t just spun by magnetism, it’s also actuated by magnetism – the starter motor itself draws a tremendous current, and drawing two contacts together in the fuel-soaked atmosphere inside your engine would be disastrous. Instead, the two contacts are drawn together using an electromagnet. Different cars require different components; whether you’re looking for a Mercedes, BMW or Audi starter motor, you’ll find one online.
In order to translate an electronic description of sound into something we can actually hear, we use devices known as speakers. These make use of magnetism; a fixed magnet is placed beside an electromagnet, and moves in response to current passing through the latter. On the other side, it’s attached to a cone of cardboard, Kevlar or aluminium, which is what pushes the air to generate the pressure changes which allows us to perceive sound.
Microphones work by much the same principle, except that (you guessed it) the arrangement is reversed. The changes in air pressure as a result of external sound, like a human voice, moves a mobile ribbon (or a similar device) which changes the relative position of two magnets. Speak into the microphone, and the changes in pressure will be recorded – so that they can later be played back using a speaker!
In especially high-security environments, a set of electronic locks is required. Sufficiently powerful magnets can be nigh-on immovable, and far preferable to their mechanical counterparts. What’s more, such devices can be actuated electronically, which means that they can be even actuated remotely. This computerisation means that the people who own the security door can be instantly and automatically notified by smartphone whenever there’s an unlock event. You might think that such technology is restricted to bank-vaults and other super-secure locations, but it’s finding its way into other, more mundane settings, too.
Finally, we come to a device that’s made doing the home laundry a great deal easier: the washing machine. Inside each machine you’ll find a rotating drum, whose role it is to keep your clothes moving and keep water moving around them. This drum isn’t driven by an internal combustion engine, but by a series of high-powered magnets. The same is true of tumble-driers, which use a similar drum-based approach. Without electromagnets, these devices would need to be turned by hand, or perhaps by steam-power. Suffice to say, the magnetic approach is far preferable!