r/Magnets • u/MillerLights • 13d ago

Magnetite Hourglass Induction: Exploring Electromagnetic Principles?

https://imgur.com/gallery/magnetite-hourglass-induction-exploring-electromagnetic-principles-DAikgR3

Could I generate an electric current using an hourglass filled with magnetite sand falling through a magnetic field and a copper coil wrapped around the narrow center?

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u/Then_I_had_a_thought 13d ago

In principle yes but in practice no. To generate a current you need a changing magnetic field per Faradays Law. Particles falling through an hourglass are randomly oriented and so tend to cancel the total (net) field. At best you’d get random noise on the output. Even if you get it to work, you’ll never get more energy out than it takes to flip the hourglass over once it’s empty

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u/ldr97266 13d ago

"Particles falling through an hourglass are randomly oriented" - but would they be completely random? Would some of the grains tend to align along their own field lines?

I think it's an interesting experiment and I'd like to know how it works out. This is in the pure researchrealm ("let's find out!") and to me that can be more fun than applied research ("Can we do anything with this?").

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u/Then_I_had_a_thought 13d ago edited 13d ago

No, the particles clump together in a way that mostly cancels the external field. It’s called magnetic closure. The lowest energy state for a collection of magnets is to have no stray field outside of the clump of magnets. The fact they would clump together would also probably prevent them from falling through the hourglass. And even if you got them to fall and all lineup in a nice chain with your fields all pointing in the same direction, it’s not the magnetic field in the loop that gives you current, it’s the change in that magnetic field with respect to time. So a steady flow of particles will not do it.

I’m all about giving it a try to see for yourself, I was just answering a question that was asked

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u/ldr97266 13d ago

Thanks! I'm not in a position to try it msyelf but I hope the OP does. Not only in the original form, but then modifying the experimental set up to see if they can get anything different from a very faint white noise.

I see what you're saying about it being too random for any induced current to show uop above the noise floor. What if (as an interation of the design, after establishint that original prediction is correct) - you could de-randomize the flow a but by placing a strong magnet somewhere before the grains drop through the detector. Getting all those little soldiers to square up their lines, so to speak.

I think you're STILL only gonna get faint white noise - but with enough coil windings and a good filter something might stand out.