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Homework Help: Units of electromagnetic Wave

  1. Feb 6, 2006 #1
    B = k / w ( Z x E)

    Check this equation by deriving the units for B


    w = omega
    Z = z hat
     
  2. jcsd
  3. Feb 6, 2006 #2
    What have you done so far?
     
  4. Feb 6, 2006 #3
    k = 2pi / lamdba
    w = 2 pi V / lamba

    So B = 1/V ( Z X E)

    B = 1/ [ m / s ] ( Z X E )

    [E] = [q] / [E0] [ R^2]

    [E] = [C] / [C^2/ Nm^2] [ m^2] = [N / C]

    B = [s / m] * ( Z x [N / C])
     
  5. Feb 6, 2006 #4
    but = N / A * m
     
  6. Feb 6, 2006 #5
    [C / s] = [A], so 1/[A] = [s / C]

    [N] / [Am] = [N / m]*[1/A], right? so [N]/[Am] = [s/C]*[N/m], or [s/m]*[N/C]

    I may have missed something, but I don't see a problem.

    Also, be careful. V = voltage, v = velocity. It was hard to read your posts with some of those things in caps. This could have been easier if you noticed immediately that k/w = 1/v, which has units [s/m], and that E always has units [N/C]. Maybe you were expected to work it all out, but that's silly.
     
    Last edited: Feb 6, 2006
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