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Homework Help: Distance relationship between primary/secondary coils

  1. Dec 3, 2006 #1
    We have done a simple experiment on AC transformers.
    Given: AC Supply. Big primary coil. Smaller secondary coil. Even smaller metal rod. (They all fit into each other) Voltmeter
    What we did:
    Connected AC supply to the primary coil. Voltage kept constant at all times
    Secondary coil was placed in the primary coil, and connected to a voltmeter.
    Secondary coil was raised X distance from the primary coil. (Measured top to top).
    Voltage on the secondary coil measured with each step.

    Now, our results (Voltage vs. Distance) showed parts of a sin (or cosine) graph, and we are having a hard time justifying it. (i know that flux is BAcos(theta)
    I would be very pleased if someone could explain it.

    Thanks in advance
  2. jcsd
  3. Dec 4, 2006 #2


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    Staff: Mentor

    What equation should govern the pickup voltage as a function of distance? What equation describes the 3-D shape and intensity of the magnetic field created by a wire loop?
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