Electromagnetic confinement and Oscillators

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Discussion Overview

The discussion revolves around the feasibility of using oscillating electromagnets to suspend ferrofluid in an acrylic chamber. Participants explore the theoretical and practical aspects of this concept, including the frequency of oscillation, the nature of magnetic fields, and the implications for radio communication.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • One participant proposes using two electromagnets oscillating at 1 GHz to suspend ferrofluid, questioning if this frequency is sufficient to achieve levitation.
  • Another participant expresses skepticism about the practicality of generating a 1 GHz signal and suggests that a lower frequency, such as 10 kHz, may be more effective due to circuit behavior considerations.
  • Concerns are raised about potential interference with radio communications if the apparatus inadvertently acts as an antenna.
  • Participants discuss the mechanics of how switching electromagnets on and off could theoretically affect the position of the ferrofluid, with one questioning whether this would result in actual levitation or if gravity would dominate.
  • There is a suggestion that a sketch of the proposed setup could clarify the concept, including the shape and dimensions of the acrylic chamber and the ferrofluid's behavior within it.
  • Another participant mentions an alternative method of suspension using coils to create a varying magnetic field, which could stabilize a magnetic item in a vertical tube.

Areas of Agreement / Disagreement

Participants express a range of views on the feasibility and mechanics of the proposed idea, with no consensus reached on the effectiveness of using 1 GHz oscillation for suspending ferrofluid or the implications of such an experiment.

Contextual Notes

Participants note limitations regarding the assumptions made about the behavior of magnetic fields at high frequencies and the practical challenges of conducting such an experiment, including the need for specialized equipment and potential regulatory issues.

Who May Find This Useful

This discussion may be of interest to those exploring experimental physics, electromagnetism, and applications of ferrofluids, as well as individuals considering innovative methods for magnetic levitation.

TheAmatuerHobbyist
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I am wondering if it is possible to use two electromagnets oscillating at about 1 ghz to suspend an amount of ferrofluid in an acrylic chamber. As I understand it, 1 ghz should be sufficient enough to get the ferrofluid away from each magnet, as after a quick google search, magnetic fields move at the speed of light. I could be wrong though, I don't really know what I'm talking about. TIA for any answers.
 
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Well, I'm a bit old school and like to get my hands dirty and experiment, but I say give it a try! After all...

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Just be mindful of safety and your own limits of expertise and equipment. I'm curious to know it it works!
 
Welcome to PF. :smile:

TheAmatuerHobbyist said:
I am wondering if it is possible to use two electromagnets oscillating at about 1 ghz to suspend an amount of ferrofluid in an acrylic chamber. As I understand it, 1 ghz should be sufficient enough to get the ferrofluid away from each magnet, as after a quick google search, magnetic fields move at the speed of light. I could be wrong though, I don't really know what I'm talking about. TIA for any answers.

Please post some links to your reading about this. It's hard to know how to respond to your question without seeing what you have been reading.

I don't think I've ever seen an "electromagnet" driven at "1GHz" before. Can you show us a link for that?

And unless you have several $100k handy, it's unlikely that you would be able to put together the 1GHz signal generator and RF power amp to generate this drive signal. And unless you have access to a shielded enclosure to conduct this experiment, you will likely get a visit pretty quickly from the FCC (or similar agency depending on your country) to have a talk with you about interfering with the radio communication in your area... :wink:
 
berkeman said:
Welcome to PF. :smile:
Please post some links to your reading about this. It's hard to know how to respond to your question without seeing what you have been reading.

I don't think I've ever seen an "electromagnet" driven at "1GHz" before. Can you show us a link for that?

And unless you have several $100k handy, it's unlikely that you would be able to put together the 1GHz signal generator and RF power amp to generate this drive signal. And unless you have access to a shielded enclosure to conduct this experiment, you will likely get a visit pretty quickly from the FCC (or similar agency depending on your country) to have a talk with you about interfering with the radio communication in your area... :wink:
I don't have any articles for this info, just asking if it would be possible. To clarify, my idea is to use a DC power supply to switch each electromagnet on/off 1,000,000,000 times a second, or 1 GHz. Don't know if would work though. Also, why would it interfere with radio communication?
 
TheAmatuerHobbyist said:
Also, why would it interfere with radio communication?
Just what exactly do you think radio communication is?
 
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TheAmatuerHobbyist said:
I don't have any articles for this info, just asking if it would be possible. To clarify, my idea is to use a DC power supply to switch each electromagnet on/off 1,000,000,000 times a second, or 1 GHz. Don't know if would work though.
Why would switching an electromagnet on and off provide levitation of a ferrofluid? You must have read something about that somewhere, no? Let's start with some links to that please. Thank you.

And you can't just specify some arbitrarily high frequency to drive the electromagnets; electromagnetism and circuits don't work like that. It's much more practical to drive a small electromagnet with 10kHz instead of 1GHz. As a drive frequency increases, parasitic capacitance and inductance play a larger role in the overall circuit behavior.

TheAmatuerHobbyist said:
Also, why would it interfere with radio communication?
Because if you are trying to drive a 1GHz signal into a test apparatus, it is way too easy for parts of the apparatus to act like little transmit antennas, and your transmitted signal can interfere with other communications at that frequency (and its harmonics if your drive waveform is not a pure sine wave).

Amateur radio operators like myself and @Averagesupernova are some of the people that the FCC uses to hunt down interfering noise sources, so depending on where you are, I could be one of the people knocking on your door to have a chat... :wink:
 
berkeman said:
Why would switching an electromagnet on and off provide levitation of a ferrofluid? You must have read something about that somewhere, no? Let's start with some links to that please. Thank you.
Well, magnetic fields move at the speed of light, which is 299 792 458 m/s. A 1 GHz DC signal would oscillate at 1,000,000,000 Hz. That means that the electromagnets would be turned on/off 1,000,000,000 times a second. If i invert the signal for 1 electromagnet, that means when one is off, the other is on. Then, shouldn't it be attracted to 1, then be attracted to the other, and so on? Shouldn't that mean it doesn't really go anywhere? As I said in my original post I could be wrong, and I was wondering, not once did I claim to know what I was saying.
 
TheAmatuerHobbyist said:
Shouldn't that mean it doesn't really go anywhere?
On average, the magnets may as well not be there, so gravity will win.
 
Baluncore said:
On average, the magnets may as well not be there, so gravity will win.
Is there a way to fix that? Perhaps run it at a different frequency?
 
  • #10
TheAmatuerHobbyist said:
... to suspend an amount of ferrofluid in an acrylic chamber.
Maybe a sketch would help.
What shape acrylic chamber?
Will the fluid rest against the acrylic anywhere?
What volume and shape ferrofluid?
Why do you want to "suspend" the fluid? Against gravity?
 
  • #11
Baluncore said:
Maybe a sketch would help.
What shape acrylic chamber?
Will the fluid rest against the acrylic anywhere?
What volume and shape ferrofluid?
Why do you want to "suspend" the fluid? Against gravity?
I don't have a sketch, right now this is an abstract idea. The acrylic chamber would be cylindrical, with the electromagnets on either end. the fluid would not touch the acrylic chamber, and doesn't need to be a specific volume. I assume the shape of it would be determined by the magnetic fields, but I could be wrong. Also it would be against gravity, I guess in the middle of the chamber.
 
  • #12
You can suspend a magnetic item in a vertical tube, by winding many turns of wire around the tube. You vary the current through the coil to vary the magnetic field. That current is adjusted to maintain the vertical position of the item in the tube. If you sense the position with a light detector from outside the tube, the current can be adjusted to stabilise the item automatically.

Is the tube axis vertical or horizontal?
 
  • #13
Baluncore said:
You can suspend a magnetic item in a vertical tube, by winding many turns of wire around the tube. You vary the current through the coil to vary the magnetic field. That current is adjusted to maintain the vertical position of the item in the tube. If you sense the position with a light detector from outside the tube, the current can be adjusted to stabilise the item automatically.

Is the tube axis vertical or horizontal?
The tube axis is vertical, but I would like to see the ferrofluid hovering, attached to nothing. I will keep the coil idea in mind though, thanks.
 
  • #14
TheAmatuerHobbyist said:
I will keep the coil idea in mind though, thanks.
That suspension technique is used to weigh gas produced from small samples.
 
  • #15
So drawing and uploading a sketch is too much work for you, but figuring out what you mean from a sketchy (get it?) description is not too much work for us? People might start drawing conclusions.

What I think you are saying is that you turn on the upper magnet and them your material gets pulled up. A nanosecond later you switch directions and your material is pulled down. Then you switch again and again and again and it stays in position.

This will not work, no matter how "cool" you think it is:

1. As @Baluncore points out, gravity is still there.
2. Even if that wen't the case, as @berkeman points out, having an electromagnet switch directions a billion times per second is not (edit: fixed) consistent with the inductance you need.
3. Even if that wen't the case as well, you have not described a system with any kind of lateral restoring force, so your material will exit the sides.
 
Last edited:
  • #16
berkeman said:
I don't think I've ever seen an "electromagnet" driven at "1GHz" before.
Perhaps a tuned loop, top and bottom?
 
  • #17
I think the point is that the inductance of that electromagnet is so big it will look like a brick wall to 1 GHz AC.
 
  • #18
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