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: Excited evanescent wave

  1. Mar 12, 2016 #1
    1. The problem statement, all variables and given/known data
    A glass prism is used to launch an evanescent wave along a glass-air interface. What is the minimum incident angle to excite the evanescent wave?

    2. Relevant equations

    3. The attempt at a solution
    I dont understand what the question is asking for. I have read and reread the section in my book about evanescent waves it doesn't say anything about this? what does the question mean by "excite"?
  2. jcsd
  3. Mar 12, 2016 #2


    User Avatar

    Staff: Mentor

    I believe they are referring to the waves that occur in the close proximity to an interface where total internal reflection is occurring (which should be a strong hint as to what sort of angle you are looking for). One might think that nothing "gets across" the barrier presented by the interface when total internal reflection is occurring, but there are very short range field effects generated there.
  4. Mar 12, 2016 #3
    thats what i was thinking. we've spoken about total internal reflection and its in the context of evanescent waves in the text. thank you!!!
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted