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Homework Help: Electromagnetic wave reflects off a surface at a 90 degree angle. Standing wave?

  1. Jan 24, 2009 #1
    What happens when an electromagnetic wave reflects of a surface at an 90 degree angle and continues moving along the same path as it came from?

    Will the two waves that are moving in opposite direction interfer with each other to from a standing wave pattern?

    This seems to be the case when you tie one end of a string to something and then move the other end to form a wave like pattern. After having reflected the 2 waves create a standing wave.

    I doubt this happens with electromagnetic waves, but I have no to way to test it. Can electromagnetic waves form standing waves under any conditions?

    Thank you.
  2. jcsd
  3. Jan 24, 2009 #2
    Electromagnetic waves do interfere. This is the reason the double slit interference pattern occurs on a screen when the two coherent sources are focused. Also, this interference principle is used to produce antireflection and high reflecting coatings, and narrow bandpass optical filters (the optical fiber system this information was transmitted on and received by you is in part due to optical filters). Yes, an electromagnetic wave can be a standing wave, for example, in a laser cavity.
  4. Sep 27, 2009 #3
    Do you mean to say, a EM (plane wave) at normal incidient angle with a boundary ?

    Yes. There would be standing wave as explain by Fresnel reflection and refraction.
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