We have already seen connections between electricity and magnetism. A magnetic field surrounds a current. Previously we saw that a magnet can exert a force on a moving charge. Therefore, a magnetic field can exert a force on a current-carrying wire or exert a torque on a current loop. Nowthe connections between electricity and magnetism will be extended. A magnetic field can cause a voltage or a current. With that we will have come full circle--a current causes a magnetic field and now a magnetic field will cause a current. Electricity and Magnetism are not separate; rather, they are two aspects of a single concept--Electromagnetism.What we learn in this chapter provides the basis for generating and transmitting electricity. This is very important for it involves the very electric power that provides electricity to all the things we so readily take for granted--lights, television, computers, fans, refrigerators, and stereos to name only a few.
The ideas presented in this chapter were first understood by Michael Faraday in England and Joseph Henry in the United States in 1820 and 1821. Both investigated these ideas independently. Henry's work was established to have occurred first but Faraday's work was reported and published first and was more thorough.
(c) Doug Davis, 2003; all rights reserved
Return to Ch 21, Electromagnetic Induction
