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Some more electromagnetism questions (ac generators)

  1. Nov 30, 2005 #1
    A few more questions that i am stuck with:
    An AC generator has a coil area of 120cm². The coil has 100 turns. The generator produces a peak voltage of 29V when the coil is turning at 6000 revolutions per minute.
    Calculate the magnetic flux density (assumed uniform) required.

    The rate of rotation is reduced to 3600 revolutions per minute.
    Calculate the new peak output voltage and the new output frequency. (I calculated the old frequency before and found that it was 100Hz).

    A wire is bent into the shape of a semicircle of radius 0.2m. A uniform magnetic field which has a flux density of 0.8T acts normally to the plane of the semicircular wire. As the wire is rotated at a constant rate it generates an alternating EMF with a peak value between the terminals 0f 0.31V Calculate the angular speed at which the wire is rotated.

    Ive been trying to use the formula EMF = ωNABsinθ but without success.
    Sorry, im just having trouble answering these without a teacher to help :redface:
    Thanks again for any help in advance.
  2. jcsd
  3. Nov 30, 2005 #2


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    Homework Helper

    The formula for EMF you are using seems reasonable. Maybe it's your math, so if you could write out some of your calculations.
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