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  • I've got two bits of metal.

  • This is an aluminium cylinder.

  • So long on a similar cylinder of near Damien on.

  • These two are gonna pass through a copper cylinder.

  • Can you see down it?

  • Yeah, right away.

  • Through.

  • Now then.

  • This is the cup, too, with an aluminium soda, and I'm gonna put it in there and no force will be exerted on this, apart from gravity.

  • So doing a quick some that's gonna fall down in about 1/3 of a second.

  • Just about court it, dear.

  • So that's how quickly the aluminium fools Now I'm going to put the near Damien in the abdomen is one of these new magnets.

  • It's incredibly powerful.

  • 234 After about a count of four, slow counter for maybe four seconds, it comes out.

  • So this is more than 10 times as long as the aluminium.

  • As this magnet falls down, say, gets to there.

  • Then it's inducing currents which will be coming around this way.

  • And these currents coming around this way will induce a magnetic field pushing in the opposite direction.

  • So as this comes down this imagine a magnet that I've got is going to be pushing in the other direction, holding it up, holding it up, stopping it from accelerating.

  • And it gets to a finite for lost E, which it travels all the way down the cylinder.

  • I'm gonna put the copper tube inside an aluminium cylinder.

  • I'm gonna put the near Damien magnet in.

  • And the question is, what's gonna happen as the near Damien magnet falls through?

  • That a little aluminum cylinder?

  • Is it gonna stay still is gonna be pulled up?

  • Is it gonna move it all or does it just say stationary at first sight?

  • You might think nothing can permeate through this copper cylinder.

  • Nothing could happen it all.

  • It might shield it, but this is happening very, very slowly.

  • So I'm now gonna drop it and you can see what happens.

  • And you see, as the magnet went past this, it pushed it down.

  • Even though it wasn't touching anything, it pushed it down.

  • If I do that again in case that wasn't so good.

  • All right.

  • This isn't about magnetic attraction as you would attract a paper clip This if I move this very slowly, the aluminium does not pull towards the new demon magnet.

  • This only works when the magnetic field that comes out of here thread through this hole.

  • If I put it on the side, nothing happens.

  • But if it thread through the hole, then it will move.

  • If I move the magnet down to here, the magnetic field is not threading through this hole in any appreciable amount.

  • So put it there and it doesn't attract a tool if I put it there, then the magnetic field through thread through the hole.

  • But if I move it very, very slowly in words, nothing much happens.

  • But if I move it out quickly without touching the sides, the magnetic field is changing rapidly.

  • The part that threading through that hole that's inducing a current in the outside, they're attracting each other.

  • That's weird, because this is, without anything happening, a force between these two, which depends upon the speed at which I pulled right away.

  • What do you seeing that?

  • That's nothing.

  • So why don't we drop something through it?

  • Just make sure it's a thing.

I've got two bits of metal.

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B1 中級

更多磁石 - 六十個符號 (More Magnets - Sixty Symbols)

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    林宜悉 發佈於 2021 年 01 月 14 日
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