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Homework Help: Amplitude of a magnetic field of an electromagnetic wave

  1. Jun 27, 2012 #1
    If the intensity of an electromagnetic wave is 80 MW/m^2, what is the amplitude of the magnetic field of this wave? (c = 3.0 x 10^8 m/s, permeability of free space ''miu subzero''= 4π × 10^-7 T ∙ m/A, permittivity of free space ''E subzero'' = 8.85 × 10^-12 C^2/N ∙ m^2)

    80MW/m^2= 80,000,000 W/m^2

    (80x10^6)(4pi x10^-7)/ 8.85x10^-12 = 1.132x10^13 ????
  2. jcsd
  3. Jun 27, 2012 #2


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    Your calculation is not correct. Why did you set it up that way? What equations have you learned that are relevant to this problem?
  4. Jun 29, 2012 #3
    If I use E0 = √2N(√μ0/ε0) this whould be the value of Electrical amplitude, but I don't know how to relate this to the magnetic amplitude.

    Could anyone else give this a go?
    Last edited: Jun 29, 2012
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