EMF problem

Discussion in 'Homework Help' started by kone, Jan 29, 2007.

  1. kone

    Thread Starter New Member

    Nov 19, 2006
    5
    0
    Can anyone help me with this problem?

    I have calculated the answer but I am not confident that it is correct.

    "Calculate emf generated in a current-carrying coil of 500 turns and cross-sectional area 5cm2 when a flux density of 0.2T density in it is reversed (changed to the opposite polarity) in a time of 10ms."

    My understand is as follows.

    If Flux Density = Flux/Area Then Flux = Area * Flux Density

    Therefore .2T = Flux/5cm2 Then Flux = (.0005m2) * .2T which is .0001wb

    so Intial Flux = .0001wb

    Then flux density is changed to opposite polarity, am I right in thinking 0.2T becomes -0.2T?

    If so then Flux Density = Flux/Area Then Flux = Area * Flux Density

    So -.2 = Flux/5cm2 Then Flux = (.0005m2) * -.2 which is -.0001wb

    Then Final Flux = -.0001wb

    Then using lenz law

    -500(-.0001 -.0001)/.01

    -500 (-.0002)/.01

    = .1/.01

    = 10V

    10V seems to high to me......

    Any help would be greatly appreciated,

    Kone
     
  2. kone

    Thread Starter New Member

    Nov 19, 2006
    5
    0
    bump bump ;-)
     
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