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The Sound of Science - 'Floating Magnets'


Jeremy: Welcome to the Sound of Science on WNIJ. I’m Jeremy from NIU STEAM. 

Sam: And I’m Sam. Today’s question comes from Abus from Rockford.

Abus: I would like to know: why does magnetism make an object float? 

Jeremy: That’s an excellent question, Abus. I think most of us know that magnets can attract or repel each other depending on which way they’re facing. You might’ve even seen objects that seem to float in mid-air by using this magnetic force to oppose the force of gravity.

Sam: To answer your question, we’re going to take a trip back to early days of electricity. In 1820, a physicist named Hans Christian Orsted noticed that when electricity moves through a wire, it creates a magnetic field around that wire.  If the wire is wrapped into a coil and electricity is run through it, we create an electromagnet.

Jeremy:  Like all magnets, electromagnets have 2 poles; a north pole one end of the coil, and a south pole on the other.  The north pole will attract the south pole of another magnet, while two north poles will repel each other.

Sam:  Magnetic levitation works by harnessing this effect to counter the force of gravity.  There are a couple of ways we can use magnets to levitate objects.

Jeremy: One way is to use permanent magnets that don’t need electricity.  By placing several magnets in such a way that they repel another permanent magnet, we can levitate small items on top of that floating magnet. This is how some of the simple desk toys that we’ve all seen work.

Sam:  Another way is to use electromagnets and computers to constantly measure and adjust the strength of the magnetic fields.  This allows us to levitate much heavier objects with much greater precision.  Many railroad companies, especially in Asia, are developing tracks that can hold the weight of a 50-ton train above the track without touching it.

Jeremy: For these Maglev systems, the tracks have strong electromagnets that only turn on when the train is above it. The train cars also have electromagnets, flipped so they push against the magnets in the tracks. Computers then control the amount of electricity flowing through these magnets, creating just the right amount of repulsive force to perfectly balance out the weight of each car.

Jeremy: Keep those questions coming by emailing us at STEM Outreach at NIU dot EDU. This has been the Sound of Science on WNIJ.

Sam: Where you learn something new every day.

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