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Homework Help: Total Power Radiated

  1. Nov 16, 2011 #1

    PassThePi

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    What is the total power radiated by an isotropic source in free space is |E| = 1mV/m at a distance of 10km?

    Relevant Eqns:
    Prad(theta,phi,r) = (1/2)*eta*|E|^2

    Prad(theta,phi,r) = (1/2)*377*0.001^2*(10000) = 1.885mV

    Is this correct? I feel like it can't be that simple.
     
    Last edited: Nov 16, 2011
    PassThePi, Nov 16, 2011
  2. jcsd
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  3. Nov 16, 2011 #2

    yungman

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    Your 1mV/m is measured at a point 10Km away, to calculate the total power of the isotropic source( E is equal in magnitude at any point on the sphere), you need to have some sort of integration of the whole surface of radius of 10Km.

    I don't understand your formula at all!!!
     
    Last edited: Nov 16, 2011
    yungman, Nov 16, 2011
  4. Nov 16, 2011 #3

    PassThePi

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    Oh I think I see...

    Prad(theta,phi,r) = (1/2)*eta*|E|^2

    Prad(theta,phi,r) = (1/2)*377*0.001^2*(10000) = 1.885mV

    PradTotal = (int(0|2*pi))(int(0|pi))(Prad(theta,phi,r)*r2sin(theta)dtheta*dphi

    PradTotal = 2*pi*0.132*(-cos(\0|pi)) = 0.528*pi
     
    PassThePi, Nov 16, 2011
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