An electric generator
A electric motor is a device for transforming electrical energy into mechanical energy;
an electric generator does the reverse, using mechanical energy to generate electricity.
At the heart of both motors and generators is a wire coil in a magnetic field. In fact,
the same device can be used as a motor or a generator.
When the device is used as a motor, a current is passed through the coil. The
interaction of the magnetic field with the current causes the coil to spin. To use the
device as a generator, the coil can be spun, inducing a current in the coil.
An AC (alternating current) generator utilizes Faraday's law of induction, spinning a
coil at a constant rate in a magnetic field to induce an oscillating emf. The coil area
and the magnetic field are kept constant, so, by Faraday's law, the induced emf is
given by:
If the loop spins at a constant rate,
. Using calculus, and taking the derivative of
the cosine to get a sine (as well as bringing out a factor of
), it's easy to show that the
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This note was uploaded on 11/22/2011 for the course PHY PHY2053 taught by Professor Davidjudd during the Fall '10 term at Broward College.
 Fall '10
 DavidJudd
 Physics, Energy

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