Ferrofluid in High Voltage AC Source

[etherist]

What will happen in a ferrofluid in an elastic cylindrical tank when subjected to high voltage alternating current? Is it will expand and then back to its normal dimension periodically because of repulsion?

The diagram on the attachment is the set-up, all answer will be appreciated. Thanks

 

[Bobbywhy]

Hi etherist. Welcome to Physics Forums!

You have proposed subjecting the ferrofluid to a "high voltage alternating current". Looking at your thumbnail I can see only one wire that leads to a "High voltage source". As we know, no current can flow without a complete circuit. Members here are ready and willing to offer you useful responses, but need some more information. Please give some more details.

1. Where is the "return" wire attached?
2. Do the wire(s) enter the elastic tank and make contact with the ferrofluid?

Bobbywhy

 

[etherist]

The ferrofluid is electrically connected to the top wire of a tesla coil. Is it will operate without return since i will use tesla coil? I want to test an experiment but i do not have tesla coil, and this set up of experiment is not available on youtube. Is there any vibration that will happen in the elastic tank? Thanks a lot.

 

[Bobbywhy]

The application of a static voltage would not cause any reaction by the ferrofluid.
Notice there could not be any current flow.
Even if a "return" wire was connected to the ferrofluid there would not be any reaction.
Ferrofluids are a non-conductors.
If you want the sphere to "vibrate", or move with an applied signal, you must use a magnetic field.

Bobbywhy

 

[etherist]

Thanks Bobbywhy. I am searching for ideal way of reciprocating pump much the same with the heart of arthropods works. I thought ferrofluid will help by static repulsion, but it will not cause reaction.

 

[Bobbywhy]

Piezoelectric materials move mechanically when they feel a voltage applied to them. No current needs to flow. Google that. Let us know here on Physics Forums how your project goes. If you have other questions or doubts, post them here. Members here are always to help an innovative searcher, if possible.

Bobbywhy

 

[Bobbywhy]

Peristaltic ferrofluids pump

Innovative solutions to problems we face often come to us when we observe the evolution of natural species. Some of mankind’s most important and useful inventions have come from understanding the mechanisms animals have evolved to eat, survive, and reproduce. Your idea for a pump using ferrofluids caused me to consider how artificial heart pumps function. Since ferrofluids react to magnetic fields, why not apply an alternating magnetic field? Just as a loudspeaker sends an AC voltage (current) at an audio frequency and creates an alternating magnetic field, the speaker coil vibrates and the diaphragm thus makes sound.
Google “ferrofluid loudspeakers” and “peristaltic ferrofluid liquid pump”. Now think of how our intestines have evolved to pump stuff using peristalsis.

The first example below does NOT use magnetic fields!

1. The ferrohydrodynamic pump method works when electrodes wound around a pipe force magnetic nanoparticles within the ferrofluids to rotate at varying speeds. Those particles closest to the electrodes spin faster, and it is this spatial variation in rotation speed that propels the ferrofluid forward. "We don't rely on any other material; no magnets, nothing moving but the ferrofluid that we're pumping," Koser says.
http://phys.org/news/2011-09-ma-magnetic-fluid.html

2. patent: http://www.faqs.org/patents/app/20120275929

 

[AlephZero]

Piezoelectric materials move mechanically when they feel a voltage applied to them. No current needs to flow.

If that was true, it would violate conservation of energy.

Piezeelectric materials move in response to electric charge, not voltage.

So a piezo device is electrically similar to a capacitor, not an open circuit, and current does flow when the applied voltage is changing, and the device is moving.

 

[Bobbywhy]

Oh, AlephZero! You are exactly correct! Excuse me, I posted erroneous statement(s) without thinking them through thoroughly. The application of a CHARGE to a Piezoelectric element does indeed involve some current flow, just as you describe.

Thank you for your vigilance, and for helping maintain the high standards we aim for here on Physics Forums!
Bobbywhy

 

[etherist]

Thanks bobbywhy, ferrofluid loudspeaker is a very helpful information for me. I desire to imitate how arthropods moves, using sound, thus it is necessary to design first a loudspeaker of very small size but sufficient power.