Your question is a good one. An
electric motor relies on electrical current,
either direct or alternating, that flows through
a coil of wire. This coil of wire is between the
north and south poles of a magnet. In general,
when current flows through a wire in the
presence of a magnet, a force is exerted on the
wire. This force is named the Lorentz force or
Laplace force after the men who described it. An
electrical motor is designed so that this coil
of wire turns perpetually in place as long as
electrical current runs through it. An axle is
fixed on the same component on which the wire
coil is mounted; as a result, when the current
turns, the axle turns too.
There are a lot of neat little details about
how electric motors work. In short, it's the
presence of a magnet in an electrical motor that
functions as a key ingredient in getting
movement out of electricity.
If you've got access to the internet, here is
a cool application that illustrates what I'm
talking about. Just hook up the leads, turn on
the switch, and crank the voltage! The
checkboxes in the lower left toggle the display
of the directions of the magnetic field,
electrical current, and Laplace force.
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