Homopolar generator

A homopolar or unipolar generator is an electrical generator consisting of a conducting flywheel rotating in a magnetic field with one electrical contact near the axis and the other near the periphery. In contrast to other types of generators, the output voltage never changes polarity, hence the name. The charge separation results from the Lorentz force on the free charges in the disk. The motion is azimuthal and the field is axial, so the electromotive force is radial. The electrical contacts must be made through a "brush" or slip ring, which results in large losses at the low voltages generated.

Related Topics:
Electrical generator - Conducting - Flywheel - Magnetic field - Lorentz force - Electromotive force - Brush - Slip ring

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If the magnetic field is provided by a permanent magnet, the generator works regardless of whether the magnet is fixed to the stator or rotates with the disc. Before the discovery of the electron and the Lorentz force law, this effect was inexplicable and was known as the Faraday paradox.

Related Topics:
Magnet - Electron - Lorentz force law - Faraday paradox

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