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Homework Help: Check please

  1. Mar 24, 2004 #1
    Please tell me if this is right:

    A coil contains 100 turns of wire in a loop 15cm in diameter. The loop is placed between the poles of a large electromagnet B= 1.0 T, with the plane of the loop perpendicular to the field. If the magnetic field is steadily reduced from 1.0 T to 0 in 16 seconds, is the emf in the coil = 0?
  2. jcsd
  3. Mar 24, 2004 #2
    I can tell you that it's definitely not 0, not in the first 16 seconds that is.

    [tex]\epsilon ' = \frac{d\phi B}{dt} = \frac{dBS}{dt}[/tex]
    S, the area, stays constant but B, the magnetic field, reduces constantly. So the magnetic flux through the coil changes and therefore there is EMF in it.
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