Demonstration of alternating versus direct current, using a light bulb with a long flexible filament and an embedded magnet. Put DC through the bulb and the magnetic force on the current in the filament pushes one way. Put AC through it, and the alternating current direction continually reverses the forces, making the filament oscillate wildly. Hand-made bulb sold by Don Millett; patent on bulb held by Robert Kyp. Frey Scientific may not still make the base unit.
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