PHY251 Homework Set 7
Reading:
Chapter 8
Homework:
Chapter 8, Question 1,4 Problems 1,6
Hints and Solutions
Question VIII.1
(10 points)
In the wavefunction that describes a particle colliding with a barrier in one dimension we
have elements that describe momenta going in opposite directions in the same wave
function. Does this mean that the particle "does not know what it is doing"? What is the
probability interpretation of this wave function?
Hints:
No hints
Solution:
These elements do describe particles that move in opposite direction: once squared
they signify the probability of finding a reflected particle in "front" of the barrier,
and of finding a particle transmitted "behind" the barrier. Any given electron will
either
reflect
ór
be transmitted (never both!), and the squared components of the
wavefunction describe the probabilities for these alternatives to happen.
Question VIII.4
(10 points)
In the study of transmission across a square barrier, one finds in Eq. (812) that the
barrier does not reflect when sin2
qa
= 0  that is, when
qa
=
n
π
/2 for
n
a positive integer.
Give a physical explanation of how this perfect transmission is achieved. Can you think
of a practical application of the phenomenon?.
Hints:
Attempt this question after solving problem 6 .
This preview has intentionally blurred sections. Sign up to view the full version.
View Full Document
This is the end of the preview.
Sign up
to
access the rest of the document.
 Spring '01
 Rijssenbeek
 Physics, Work, Barrier

Click to edit the document details