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Some physics problems? (Posted on 2006-04-16) Difficulty: 5 of 5
This was a problem I troubled myself with when the Physics teacher taught electromagnetism.

Assuming that we can create a gigantic alternating current generator in space, rotating a gigantic circular magnet around a gigantic wire coil to induce an alternating current, will we not get infinite energy and defeat the law of conservation of energy?

As the whole set up is in space, there is no friction whatsoever between the components though the wire naturally has some resistance. The wire's induced magnetic field can oppose the rotation of the magnet, but this can be easily be counteracted by routing a bit of energy from an external circuit to the magnet. As the magnet is circular the gravitational attraction between the circular magnet and coils cancels out. The power from the wire coil will then be connected to a device which will transmit the energy to earth via an electromagnetic wave.

The only energy inputs are that to keep the ring rotating and the initial energy input to put the setup in space. The output in energy is theoretically infinite.

SOMETHING is wrong with this argument that I later discovered myself. The Physics teacher was unable to detect it and walked away quite puzzled. Can you guys find out why this would never work?

See The Solution Submitted by Jack Lim    
Rating: 3.5000 (2 votes)

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Question E = mc^2 | Comment 3 of 13 |

It is incorrect to say there is no friction whatsoever between the components. One would need more than a perfectly circular magnet and constructed components for the generator. The Heisenberg principle would also need to be ignored, for one.

The fact that even matter has a “life” (often referred to by the term half-life) would indicate that the output could not be theoretically infinite. Both protons and neutrons, though very stable particles of matter, do decay, and particles sometimes collide with other particles, releasing their energy in a manner that the generator would not transform into the energy outputed by the generator.

Neither is Space a perfect vacuum. And matter all around our cosmos is not perfectly spread apart for the forces of gravity to have no effect on the hypothetical generator. Though much of the “loss” of energy in its transformation into electromagnetic waves might be negated, it should be easily recognized that this would not defeat the law of conservation of energy. Remember the equation E = mc2.

Assuming, as inferred by the problem, that friction, resistance and interferrence could be overcome with no loss or cost to the efficency of the energy output, the statement that we could get infinite energy from the generator is still misleading. I infer from the problem that the energy output from the generator is infinite because time is, itself, theoretically infinite, and the operation of this generator would be occuring thoughout the infinity of time This, of course, presupposes that the “universe” containing the generator remains unchanged throughout this unending period. Yet, an unchanging universe is one without energy. And without energy how could the generator operate?

  Posted by Dej Mar on 2006-04-17 01:59:53
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