Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Direction of the Maxwell stress tensor

  1. Nov 2, 2011 #1
    1. The problem statement, all variables and given/known data

    Show that in vacuum the pressure tensor of a (complex) plane electromagnetic wave only has a contribution for both directions in this bivector being
    along the direction of motion, and that contribution is equal in magnitude to
    the energy density. HINT: Choose 3 orthogonal axes along the direction of
    motion, the electric vector, and the magnetic vector.

    2. Relevant equations

    σij = ε0(EiEj -0.5[itex]\delta[/itex]ijE2) + [itex]\frac{1}{μ0}[/itex] (BiBj-0.5[itex]\delta[/itex]ijB2)

    3. The attempt at a solution

    I'm not entirely sure what this question is asking. Is it saying that the tensor only acts along the direction of motion of the EM wave?

    If so the only place I can think to begin is that when i=j the delta term is simply 1 and when they're not equal the term is 0. I'm not sure I can even use that without first showing why that happens though.
  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?