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Homework Help: Magnetic fields from power lines

  1. Apr 14, 2007 #1
    1. The problem statement, all variables and given/known data
    Well I just want to make sure I am right on this one. The question is how to steal electricity by placing a coil near a power line that carries alternating current in which the current varies sinusoidally. A.) For a single wire how should the coil be oriented to induce the maximum voltage. B.) And should the coil be placed near a high voltage wire with low current or near a wire that has low voltage but high current and explain.

    3. The attempt at a solution
    Well for a.) I think that the coil should be placed perpendicular to the wire. This would line the coil up with the magnetic field going down the middle of the coil. This would induce the most current and current is proportional to voltage in V=IR so this should be right. For b.) I would want to place the coil next to a high current wire. This is because a high current wire has a greater magnetic field which would induce a higher current and the it would be easier to get more voltage. Could someone tell me if this is correct?
  2. jcsd
  3. Apr 14, 2007 #2
    Yes you are correct.
    You could have some fun by putting numbers and formulas on that
    try to find (on the net?) some typical lines dimensions (height, distance between cables, ...) and operating characteristics (voltage, current).
    Consider some design for the "receiving" coil ...
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