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Homework Help: Production of electric current

  1. Jul 31, 2006 #1
    In which of the following situations is an electric current not produced?
    a. a loop of wire rotates in a steady magnetic field
    b. a loop of wire is stationary in a steady magnetic field
    c. the magnetic field through the loop is increasing
    d. the magnetic field through the loop is decreasing

    Ok-I know that if you change hte magnetic field then the flux would change, and therefore produce an electric current, so I think its safe to say that c an d d are both wrong. But I have no clue how the wire's movement/lack of movement in a steady magnetic field would change things....can someone help me understand that?

    thank you!
  2. jcsd
  3. Jul 31, 2006 #2

    Andrew Mason

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    Remember, the flux is the dot product of B and A: [itex]\phi = \vec{B}\cdot\vec{A} = BAcos\theta[/itex]

    Does this change when the loop is stationary in a stationary field? Does it change when the loop rotates in a stationary B field (ie. the angle between B and A continually changes)?

  4. Jul 31, 2006 #3
    Suppose that the magnetic field is vertical upward.
    Suppose you have a round loop in a horizontal plane.
    Now rotate the loop along an axis wich is horizontal.
    What will happen to the flux of the magnetic field through the loop?
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