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Motor and inductor

  1. Apr 12, 2007 #1
    In these two cases , emf will be induced in different way.
    for motor: current +B-field-->Force-->Coil rotate-->change of magnetic flux-->emf inducedd in the coil
    for inductor , when the switch suddenly openfrom closes switch, there are a sudden change of magnetic flux ,there emf will be induced

    the thing I want to ask:
    why when the coil is suddenly jammed and come to stop,there will not be any induced emf in this cases??
    isn't it just the case of inductor,there are a change of magnetic flux
    from many to none magnetic flux ???


    thank you
  2. jcsd
  3. Apr 12, 2007 #2
  4. Apr 13, 2007 #3
    Usually people that answer to posted questions, try to write theirs answers clearly and in a correct language without stupid abbreviations, like "u" four "you". I think they deserve that you write your questions clearly, without shortcuts and in a text you could show to your English teacher.
    Most people who answer your questions are not your pals. Some of them happen to be older than your actual teachers.
    If your post had not been answered, it is not that no one is able to answer. It is just that no one is willing to decode your so badly written question.
  5. Apr 13, 2007 #4


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    Staff Emeritus
    Science Advisor

    In the two examples given:
    The motor has an applied alternating current, and the time varying current induces a time varying magnetic field (which would otherwise by constant).

    In the inductor, the closing of the switch allows a time varying current. A constant current would induced a constant B-field.

    If an inductor is moving in a constant magnetic field and emf will be induced. If the inductor is not moving, i.e. stopped, then the field is constant (non-varying) and no emf is induced.

    See principle of induction motor - http://hyperphysics.phy-astr.gsu.edu/hbase/magnetic/indmot.html

    Inductance concepts
  6. Apr 13, 2007 #5
    I think it will be easier for the readers to read my question by using flow chart.I apologized for my poor english because I usually weak in expressing my point of view in English.I used to write in Chinese.Really sorry.Sorry for all the readers.Sorry for my distrubance.
  7. Apr 13, 2007 #6
    You are welcome to post questions. Just try to write them clearly.
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