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ELECTROMAGNETS C
lots of technical and industrial
uses — namely, wherever
particularly powerful magnets
are needed. Recyclers, for
example, use electromagnets
attached to cranes to lift heavy
pieces of iron. To let them go,
all they need to do is turn off
the current.
Electromagnets are also used
in speakers, electric motors,
and power plant generators.
One of the world's largest
electromagnets is found at the
European Organization for
Nuclear Research lab in
Geneva, Switzerland, with a
core made of 64,000 metric
tons of steel. (photo on p. 42)
have
happens, it creates a magnetic field around
the wire. When you turn off the flow of
current, the magnetic field disappears — so
electromagnets can be switched on and off.
Electromagnetism |
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Galvanometers
A coil of wire wound
around a compass (along
with more coils of a
thinner wire) is called a
galvanometer, a device
long used as a sensitive
gauge for electric current.
( Historic mirror
galvanometer
ELECTRO-
MAGNETS
are only
magnetic as long
as current is
flowing through
them. When that
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