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Unformatted text preview: ; 2008 Transmission structures Why is AC the solution? three-phase “live” wires to house 500,000
long-distance Winter 2008 Lecture 7 • AC, or alternating current, is necessary to carry out
• To understand why, we need to know something
about the relationship between electric current and
• Any current-carrying wire has a circulating magnetic
field around it: 138,000 69,000 7–13,000
neighborhood 7 Winter 2008 8 2 AC Electricity 02/07/2008 Electromagnet Coil UCSD: Physics 121; 2008 UCSD: Physics 121; 2008 Induced Current • By arranging wire into a loop, you can make the
magnetic fields add up to a substantial field in the
middle • The next part of the story is that a changing magnetic
field produces an electric current in a loop
surrounding the field
– called electromagnetic induction, or Faraday’s Law looks just like
a magnet Winter 2008 9 Winter 2008 10 UCSD: Physics 121; 2008 UCSD: Physics...
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