Category Archives: Physics

Levitation is for L’hovers

When you hear the word levitation, maybe you think of something like this:

I’m not saying that’s not real. (But it would not be inaccurate to say that it isn’t not unreal.)

Let’s leave magical powers out of this, though. I want to talk about the sort of levitation achieved by science.

Humans have found a handful of ways to force objects to defy gravity, and I’m going to tell you about one: magnetic levitation.

Ever heard of a maglev train? It uses electromagnets to run without touching the tracks, cutting down on friction (allowing for faster starts and stops) and wear-n-tear (theoretically making it less expensive to maintain). In order for this to work, the train has to hover at exactly the right distance from the track: 15 mm. That’s about the width of a woman’s thumb. The downside? No more nostalgic penny-smushing (possibly outweighed by the cool factor of a LEVITATING TRAIN).

Some maglevs actually use electrodynamic levitation, which involves superconducting electromagnets.

[SIREN SOUND! SIREN SOUND!]

Whoops, sorry…looks like the Too Many Fancy Scientific Words (TMFSW) alarm just went off. Let’s break this down a bit.

What’s an electromagnet?

It’s a magnet that uses electricity to produce its magnetic field.

What is a superconducting electromagnet?

An uber-strong electromagnet produced by electric current from superconducting wire.

Superconducting wire?

Yeah. It just means the wire, when brought to extremely low temperatures, can carry a bunch more electrical current than regular wires. This allows it to create really strong magnetic fields.

Is everybody good? Can we turn the TMFSW alarm off now?

[SILENCE.]

Excellent. Now, where was I?

Ah, yes. Some maglevs use superconducting magnets for levitation and propulsion. You know how when you put two magnets together at the wrong ends, they’ll push apart? A much stronger version of that force is what makes these maglevs hover and go. Here’s a basic view of how that works (remember, opposites attract, so North will push apart from North):

When you think about how heavy a train is, it makes sense that these magnets would have to be outrageously strong to levitate one. Thus, superconducting electromagnets instead of, say, Magna-Doodle dust.

Are you impressed yet?

No?

Fine. Just watch this video. If you’re not in awe of levitation after that, we’ll see about resurrecting Kellar for one last show.

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