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Colloquium Schedule

Spring 2019

Electric Power from Earth's Rotation Through Its Own Magnetic Field

Christopher Chyba ('82), Princeton University
Fri., Mar. 8, 2019, 12:30 PM in Science Center 199

If we rotate a permanent magnet about its north-south axis, does its axially-symmetric magnetic field rotate together with the magnet? What about for an electromagnet? If the axially symmetric field does not rotate with a rotating electromagnet, does this mean that the Earth is rotating through the axially symmetric component of its own internally generated magnetic field? Then what happens? Could the resulting Lorentz force be used to drive electrons around a circuit and generate electricity, powered by the Earth's rotational kinetic energy?

Michael Faraday started asking these questions in 1831. I'll review the developments since then, concluding that the Earth does in fact rotate through the axially symmetric component of its own field. I will then present a simple proof that it is impossible to use this effect to generate electric power. Finally, I will demonstrate, and explore, a loophole in that impossibility proof.