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!

2 questions about em waves

  1. May 6, 2009 #1
    1. Since skin depth is the attenuation of the wave in a conductor, this means the reflection isen't the incident wave... so what is the reflection?

    2. Water doesn't stop light since it's frequency is too high, i saw on forum it's because the big ions cant move fast enought. How can that be? Wont they move as the same frequency as the wave?

  2. jcsd
  3. May 6, 2009 #2
    The incident wave penetrates deeper than the skin layer. It makes the electrons oscillate and radiate in all directions. The waves radiated in the incident wave direction add with the incident wave. The thicker layer, the more intense the radiated wave. It happens it has the opposite sign amplitude. So the radiated and incident waves gradually cancel when you go inside.

    The waves radiated with the electrons in the opposite direction are called the "reflected" waves.

    In water there too few free electrons to radiate under the incident wave influence. Yet the same phenomenon takes place, so you have reflection from the water volume too.

  4. May 6, 2009 #3
    thanks alot!
  5. May 6, 2009 #4
    Can someone tell me why waves arent comming out of every borders since it radiates in all directions?
  6. May 6, 2009 #5


    User Avatar
    Science Advisor
    Gold Member

    The total wave does not radiate in every direction though. You can decompose any wave into being the result of a summation of point sources. These point sources radiate in all directions using a spherical wave. But the sum total of all these sources is not guaranteed to radiate isotropically.

    Either way though, for the most part there is generally some reflection of waves off of all surfaces.
  7. May 7, 2009 #6
    thanks alot for the help again!
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Discussions: 2 questions about em waves
  1. EM Wave question (Replies: 1)

  2. About EM waves (Replies: 7)