1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

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
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted