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: Transmission probability (tunneling) question

  1. Jul 17, 2011 #1
    A beam of 11 eV electrons is directed towards a barrier of potential Vo = 3.8 eV. Compute the width of the barrier for which the reflection is maximized (Note: this is NOT asking for when reflection is 100%).

    Transmission probability for E > Vo:
    T = [ 1 + (Vo²*sin²(βa))/(4E*(E - Vo)) ]^(-1)

    where a is the width of the barrier.

    I need a bit of help starting this question. I do not understand why maximum reflection is not 100% reflection, or T = 0. Finding when something is a maximum makes me think "derivative = 0," but other than that I'm really unsure about where to go. And there is a formula for β but I am not very concerned with numerical answers right now. Any advice is appreciated.
  2. jcsd
  3. Jul 18, 2011 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Education Advisor

    Why would you expect the reflection coefficient to be 1?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook