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Homework Help: Find Magnetic Field Amplitude from EM Wave Amplitude

  1. May 1, 2013 #1
    1. The problem statement, all variables and given/known data

    A plane electromagnetic wave propagating in free space has an amplitude ([itex]\sqrt{3}[/itex]/2)a[itex]_{y}[/itex]-(1/2)a[itex]_{z}[/itex] V/m. Find the amplitude of the accompanying magnetic field assuiming the frequency of the electric field is 1 GHz.

    2. Relevant equations

    f[itex]_{E}[/itex] = f[itex]_{H}[/itex]

    [itex]\frac{E_{0}}{B_{0}}[/itex] = [itex]\frac{ω}{k}[/itex] = c

    3. The attempt at a solution

    I know that the frequency for both the Electric and Magnetic fields are equivalent. Therefore, the magnetic field frequency is also 1 GHz.

    However, the question says "electromagnetic wave." This term means the cross product result or E x B right? With that being said, I'm not sure how to obtain the amplitude of the magnetic field if I don't have any info for the electric field.

    Or is there some other equation related to the EM wave?

    Any help or suggestions is greatly appreciated!
  2. jcsd
  3. May 1, 2013 #2

    Simon Bridge

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    Science Advisor
    Homework Helper

    But you are provided with "info for the electric field": the frequency and the amplitude. What else do you need?

    For EM radiation the E and B components have a special relationship.
  4. May 2, 2013 #3


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    Homework Helper

    Perhaps it was meant the vector amplitude of the electric field.

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