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Homework Help: Cant understand this transition

  1. Dec 13, 2009 #1
    http://i47.tinypic.com/2lj3uvl.jpg

    how did they erased the derivative of I object

    how did they change the variable?
     
  2. jcsd
  3. Dec 13, 2009 #2
    Substitute P=Li.di/dt in the equation.. dt cancels out
     
  4. Dec 13, 2009 #3
    why they change t to I
    on the interval
    ?
     
  5. Dec 13, 2009 #4
    Because now we are integrating with respect to i as it goes from 0 to I. First, we were integrating with respect to t which was going from 0 to t. It means that as t goes from 0 to t, i goes from 0 to I and that i is dependent on t.

    i(t=0) = 0
    i(t=t) = I
     
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