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Homework Help: Power output of radiation

  1. Feb 7, 2016 #1
    1. The problem statement, all variables and given/known data
    A solenoid contains 610 cycles, with a radius of 0.136m and a length of 0.87m. The current of the solenoid decreases linearly from the maximum value I0 to zero through the equation I(t)=I0−bt, where I0=0.31 A and b=0.21 A/s.

    What is the power output of the electromagnetic radiation at t= 0.738095238095?

    2. Relevant equations

    3. The attempt at a solution
  2. jcsd
  3. Feb 8, 2016 #2


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    Gold Member

    I am unclear why a solenoid about one metre long will radiate any significant energy when the supposed frequency is in the order of one Hertz, a wavelength of 3x10^8 metres? The presence of electric and magnetic fields does not mean there is radiation. The fields of the solenoid contain energy that is almost entirely stored and not radiated.
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