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Tags magnetism , magnets , physics

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Old 29th May 2020, 12:24 PM   #41
wardenclyffe
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I understand. But what I don't understand is the difference between a permanent magnet and an electromagnet. I mean, I understand that one is non-magnetic until electrified and the other is always magnetic. I assume that an electromagnet is generally more powerful than a permanent magnet. But is that it?

In that clock, would it be theoretically possible to use a permanent magnet if it were powerful enough, or is there some other characteristic that an electromagnet has that allows it to levitate the ball?

Ward
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Old 29th May 2020, 03:08 PM   #42
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Originally Posted by wardenclyffe View Post
I understand. But what I don't understand is the difference between a permanent magnet and an electromagnet. I mean, I understand that one is non-magnetic until electrified and the other is always magnetic. I assume that an electromagnet is generally more powerful than a permanent magnet. But is that it?

In that clock, would it be theoretically possible to use a permanent magnet if it were powerful enough, or is there some other characteristic that an electromagnet has that allows it to levitate the ball?

Ward

The electromagnet can be turned on and off, or varied in strength, very quickly and continuously as needed to keep the ball in position.
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Old 29th May 2020, 04:30 PM   #43
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So how would the clock sense where the ball is in order to regulate the magnet? I'm sure there's an easy way, but I don't see it.

Ward
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Old 29th May 2020, 05:09 PM   #44
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An old video on magnetic levitation with permanent magnets. Part 1. https://youtu.be/OI_HFnNTfyU

Last edited by Steve001; 29th May 2020 at 05:10 PM.
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Old 29th May 2020, 05:19 PM   #45
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Old 31st May 2020, 09:48 AM   #46
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Originally Posted by wardenclyffe View Post
So how would the clock sense where the ball is in order to regulate the magnet? I'm sure there's an easy way, but I don't see it.

I'm not sure it does actually sense where the ball is, in this particular case. It might create a cyclical field that happens to have a dynamically stable position for the ball. The fact that the ball must be placed at one precise point suggests this. A system that senses and adjusts should be able to recapture the ball from a larger range.

But sensing should be possible from the electromagnet itself, in theory. If an electromagnet is on, and you push a steel ball through its field, that will affect the current in the coil. The engineering of a functioning system out of that effect might be difficult, though.
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Old 9th January 2021, 12:18 PM   #47
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Image link revived plus YouTube link

Originally Posted by MattNelson View Post
...

Here's a setup using smaller magnets for the 2-pieces, with longer beams half as wide:

Video: https://www.youtube.com/watch?v=-0pIVBd0aN0

Find a few other magnet projects on my YT channel.
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Old 10th January 2021, 08:45 AM   #48
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When I was young I had some doughnut-shaped magnets. You can get them to levitate above each other permanently by putting a dowel or a pencil through the middle. I suspect that "permanent" doesn't mean literally forever, but for a long time anyway.
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