http://www.ck12.org Chapter 20. Magnetic Fields
CHAPTER
20 Magnetic Fields
Chapter Outline
20.1 Properties of Magnets
20.2 ELECTRICCURRENTS ANDMAGNETICFIELDS
20.3 ELECTRICMOTORS
20.4 ELECTROMAGNETS
20.5 REFERENCES
The interaction between moving electrons and magnetic fields can produce electricity. If a metallic wire that is part
of a complete circuit is passed through a magnetic field, the electrons in the wire are pushed through the circuit,
resulting in an electric current. An electric generator is any machine that is designed to generate electricity by
passing metal wires through a magnetic field. All that is required is to spin the axle on the generator. The largest
generators rely on turbines, which contain fan blades that spin when fluid—such as steam produced by burning coal
or wind blowing through a windmill—is forced through. The generation of hydroelectric power harnesses falling
water to spin turbines attached to electric generators. For instance, the Colorado River flows through the turbines
of the Hoover Dam, shown above, generating more than 4 billion kilowatt-hours of electricity each year for use in
Nevada, Arizona, and California.