Superconductivity Unity Device

In the Superconductivity chapter there is the following quote

If you're thinking this appears to be a form of perpetual motion, you're correct! Contrary to popular belief, there is no law of physics prohibiting perpetual motion; rather, the prohibition stands against any machine or system generating more energy than it consumes (what would be referred to as an over-unity device).

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The part that I question is the to part highlighted in bold. Is this not exactly what scientists today are trying to do with Fusion Reactors? They are trying to get more energy out than what they put in. To my knowledge they have not yet been able to break-even but when they do (and I believe they will) would this not constitute as an "over-unity device" ?

<_< as far as my knowledge goes on nuclear reactors(and mind u it is very limited) energy produced is less than the energy supplied...of course when we talk of energy we mean mass and energy...which are equivalent forms
in other word all logic prohibits the making of a over unity device.
but again modern physics and logic never went hand in hand

Hi,

The functional fusion reactor will produce enough energy output to sustain the magnetic containment fields and have a fractional excess left over to do useful work besides. To become an over-unity device, it would have to produce more energy than could be supplied by fusing all the hydrogen nuclei present.

Originally posted by beenthere@Jan 5 2005, 02:14 PM
Hi,

The functional fusion reactor will produce enough energy output to sustain the magnetic containment fields and have a fractional excess left over to do useful work besides. To become an over-unity device, it would have to produce more energy than could be supplied by fusing all the hydrogen nuclei present.

[post=4434]Quoted post[/post]​

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Thank you both for your input, that makes alot of sense.

But now that I reflect upon the original quote in my first post, I believe that a superconducting ring of current is not a perpetual motion machine because energy is required to keep the ring in a superconductive state. That energy being the necessary work to compress nitrogen gas into liquid N2 which is then used to cool the ring into its superconductive thermodynamic state. Without additional N2 ( and thus additional energy ) the superconductivity atribute would seize to exist.

Comments?