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Magnetic Flux (Induction - Magnet through a coil)

  1. Aug 6, 2007 #1
    Is the incoming flux (first peak) equal in magnitude to the outgoing (second peak) flux? Why?

    A magnet was dropped through a solenoid, this experiment was completed twice, a graph of Voltage (V) vs. Time (t) was made for each experiment. The area under each curve is defined to be equivalent to the Magnetic flux.

    1st time the magnet was dropped with the north pole facing down. The negative first peak had A = 0.0137 with current moving CCW and the second peak was positive with A = 0.0141 with the current moving CW.

    2nd time the magnet was dropped with the south pole facing down. The first peak was positive with A = .01095 with current moving CW and the second peak was negative with A = 0.0117 and current moving CCW.

    The percent differences are low enough to be dismissed ( I'm assuming ) and the respective area's should have equal magnitudes. The graph shows that the voltage spikes higher in the second peaks but over a shorter period of time. Potential energy is conservative so the voltages should have equal magnitudes with different signs. I can not however find a way to back it up other using any of Maxwell's equations. I have used Lenz's law as my basis as well as attempting to find a derivative of Amperes Law to back up my answer to no avail.

    A small hint or push in the right direction ( or a slap if I am completely wrong :redface:) would be greatly appreciated
  2. jcsd
  3. Aug 8, 2007 #2
    Well, you could have either turned the solenoid upside down or the magnet upside down (relatively). You chose to turn the magnet over, and found that energy is conserved in both cases (something Lenz's law will tell you). If all you have to do is show that as your data has, mostly, confirmed conservation laws then just back it up with Lenz's/Faraday's Law.
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