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Homework Help: A unit magnitude EM Wave?

  1. Nov 21, 2012 #1
    A "unit magnitude" EM Wave?

    1. The problem statement, all variables and given/known data
    Write down the solution of Maxwell's equations corresponding to a plane polarised EM wave of unit amplitude and wavelength λ=2∏m, polarised in the zy plane and travelling in vacuo in the minus y direction.

    2. Relevant equations
    ∇.E = 0
    ∇.B = 0
    ∇xE = -dB/dt
    ∇xB = με(dE/dt)
    (they're meant to have subscript noughts...)

    3. The attempt at a solution

    Ok, so polarised in zy plane means E in z direction, B in x direction. λ=2∏m, combined with the fact that the speed is c, gives (1/m(y+ct)) as the argument.

    So I have E=zcos(1/m(y+ct)) and b=x(1/c)cos(1/m(y+ct))
    (z and x meant to be unit vectors) since there has to be a factor 1/c between their amplitudes...

    Now this is probably a really stupid question, but what exactly does "unit amplitude" mean? Because, I mean, there are two waves - E and B. And if E has unit amplitude then B has amplitude 1/c...
    Last edited: Nov 21, 2012
  2. jcsd
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