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The Laws of Faraday & Lenz
BlackBoard Notes

 

  • Use a changing B to induce an Emf (and, hence, I) in a coil
  • Use Faraday and Lenz to determine the polarity of an unknown magnet.

    Faraday's Law:

    Faraday's Law

    1. Galvanometer (detects presence and direction of I):
      • Correlate direction of needle with direction of I.
          YOU MUST USE THE 100 kΩ RESISTOR

    2. Induce I with permanent magnet.
      • Eight sketches! Confirm results with right hand rule!!

      Show induced
      I & B in coil!      		 Coil

    3. Induce I with electromagnet:
      • Four sketches! Show the induced I & B in detector coil.

    4. Exit test: Use Faraday/Lenz to determine polarity of (unknown) bar magnet, and explain your reasoning!

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    © St. Lawrence University Department of Physics
    Revised: 19 Apr 04 Canton, NY 13617