Sunday, 20 March 2011

PMM Scam detected...

Facebook ads have thrown up a perpetual motion machine for my perusal. It is a direct scam and the proposed machine is not even original: it was designed  by J. Naudin. It involves a bunch of magnets rotating to present their poles to solenoids, but it is not clear why Naudin thinks this will actually turn. As it stands, it will work as an inefficient generator.

Such machines are easy to test - give it a twirl and it slows down: but the inventor claims that it slows down more slowly because, if he could only reduce the friction enough, it would keep turning forever while generating useful energy.

To test, therefore, spin it up, put it under load, time how long it takes to come to rest. Replace the magnets with inert iron bars (keeping the weight, load and geometry but removing the magnetism) and repeat. I expect that the non-magnetic (2nd) version will stay spinning for longer. Why? Because the magnetic poles moving past the solenoids puts an additional drag on the motion ... that is what is generating the electricity, and it is why you have to drive electric generators somehow to keep them going.

For more on the mystery of the perpetuum mobile and why it ain't so, please see this faq.

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