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Did you know that nearly all the electricity we use is
generated from magnets? All it takes are coils of wire, strong magnets and a
relative motion between the coil and the magnet. If you come to our booth you will get the chance to generate electricity with your muscles, and see the electricity to power
lights and other gadgets.
Magnets create magnetic fields (dashed lines). The magnetic
fields induce a voltage in a coil of wire as they pass by. This induced voltage
causes current to flow in the coil. We measure this current using a device
called an ammeter.
The key concept is that there must be a change in magnetic field in order to induce the current. The
faster the change (the faster the magnet moves past the coil), the larger the
induced voltage and current. This phenomenon is described by Faraday’s Law.
All electrical generators use this concept to generate
The hand crank generator consists of two main parts: the
Stator and the Rotor (in the figure below). The Stator is stationary and consists of the coils of
wire. The coils of wire are connected in series in order to increase the
voltage. The coils are wrapped around thin pieces of metal to increase the
effects of the magnetic field. The rotor holds the magnets. It rotates as the generator
handle is cranked. The magnets are recessed in an aluminum plate and can be
difficult to see.
As you rotate the handle, you establish a relative motion
between the coils and the magnets. The result is electricity, which can be used
to power lights and other gadgets. Rotating the crank faster makes the lights brighter
as more electricity is being generated.
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