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

Complex amplitude of E-field and phase changes

  1. Apr 10, 2010 #1

    I'm looking through my notes on em waves in dielectrics and the fresnel equations and I've been stuck on this for a while.

    It states that if the complex amplitude = E0e is positive there is no phase change. However when the value is negative, the phase change Φ is π.. Why is that?

    Thanks in advance!
  2. jcsd
  3. Apr 10, 2010 #2
    It just means that after reflection from the surface of an insulator, then the reflection coefficient (the fraction between the incoming and reflected amplitude) might be either negative or positive. If positive, there is no phase change. If it is negative, then it means that the reflected E-field "points the other way" compared to the incoming E-field - which is just a π-change in phase (recall exp(iπ) = -1).
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook