LED from Nothing?

You can make an LED operate WITHOUT a typical power source. Get an LED and attach to an induction coil (any large coil of wire wrapped around a wood or cardboard tube should do). Now, take a bar magnet and jam it thru the coil back and forth as quickly as possible. The LED will flash. Why? The moving magnet sets up an induced AC electric current in the coil and the light goes. Also, it is a cool demo to use a galvanometer in place of the LED. The kids actually see the current being created in BOTH directions as the magnet moves in or out.


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