Magnetic parachute

(ORDO NEWS) — Many even quite adult people do not understand the connection between magnetism and electricity.

Meanwhile, this connection underlies almost all modern electrical engineering – from generators to electric motors. And the easiest way to show it is with an ordinary magnet and a piece of copper pipe.

For the experiment, you only need two things – a neodymium magnet (preferably cylindrical) and an ordinary metal pipe made of a non-magnetic material, such as copper.

The inner diameter of the pipe should be slightly larger (say, one and a half to two times) than the outer diameter of the magnet. Well, now try to just drop the magnet on the floor – for the first time outside the pipe.

Magnetic parachute 2As the magnet falls, the magnetic flux in the pipe changes in such a way that it induces (induces) an electric current, the direction of which is determined by the Lenz rule. This current in turn generates a magnetic field.

If you are not as tall as Uncle Stepa, then after about half a second you will hear the characteristic knock of a magnet on the floor (and if you are still Uncle Stepa’s equal, then it will take 0.1 seconds more).

Now pick up the magnet from the floor and drop it inside the vertically oriented pipe. And while you are waiting for the appearance of a magnet from the bottom cut of a completely non-magnetic (but certainly conductive!) Pipe, let’s try to explain why this takes so long.

Magnetic parachute 3The simplest explanation of the observed phenomenon is based on two basic principles of electromagnetism: 1. A change in the magnetic field induces an electric current in the surrounding conductors. 2. An electric current generates a magnetic field associated with it. The fall will be retarded regardless of the orientation of the magnet (and even if flipped during the fall).

By the way, you can look into the pipe through the upper end – is there a magnet stuck there? No, it’s not stuck – it just falls very slowly.

The reason for this is the inseparable connection between magnetism and electricity. The movement of the magnet generates a change in the magnetic field, which, in turn, induces circulating circular currents in the pipe.

Magnetic parachute 4Above a falling magnet, the magnetic flux decreases. The direction of the current is such that the magnetic field of this current attracts the magnet from above, slowing down the fall.

And these currents generate magnetic fields that interact with the field of the magnet, slowing down its fall. Well, now you know the reason and you can show your friends a spectacular trick. More precisely, you can do it when the magnet finally flies the pipe to the end.

And here is the magnet!

Magnetic parachute 5Under a falling magnet, the magnetic flux increases. The direction of the current is such that the magnetic field of this current repels the magnet from below, also slowing down the fall.


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