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: Transmisson and Reflection (Quantum)

  1. Oct 21, 2014 #1
    1. The problem statement, all variables and given/known data
    Suppose a 12.0eV electrons approach a potential barrier of height 4.2eV.

    For what barrier thickness is the reflection at a maximum?

    (I have converted from eV to J to make the units work)

    2. Relevant equations
    (Where T is the transmission probability and R is the Reflection)

    3. The attempt at a solution

    so then q=1.42*10^10
    I plugged in q into my equation for T and then the v_0 and the E for the electron. I set all of it equal to zero, but I think that's my downfall. Conceptually T cannot be zero because L would have to reach infinity. I am not sure what is means by R being a maximum (aka L is a minimum) without setting T=0.
  2. jcsd
  3. Oct 22, 2014 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper
    Education Advisor

    T will not vanish even if L goes to infinity. This should make sense since the particle has more energy than the barrier height.

    Try looking for when T is minimized, not 0.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted