MERLOT - Multimedia Education Resource for Learning and Online Teaching
Home Communities Learning Materials Member Directory My Profile About Us

Peer Review

Become a Member | Log In

Steps and Barriers in One Dimension

by Manuel Joffre
 

Ratings

Overall Rating:

4.33 stars
Content Quality: 4 stars
Effectiveness: 5 stars
Ease of Use: 5 stars
Reviewed: Jan 12, 2002 by Physics
Overview: An applet that illustrates the time dependent behavior of a gaussian wave packet as it encounters a step potential barrier. The parameters are those of an electron moving in GaAs. The user can choose between an infinite step or finite barrier, and can vary the barrier height and width. This item is part of a larger site (http://www.quantum-physics.polytechnique.fr/)containing several related items.
Learning Goals: The user will gain qualitative information regarding the effects of changing the barrier thickness and the "height" of the potential step, on the gaussian wave packet.
Target Student Population: Introductory to upper-level quantum mechanics.
Prerequisite Knowledge or Skills: Basic quantum mechanics.
Type of Material: Java applet.
Technical Requirements: None

Evaluation and Observation

Content Quality

Rating: 4 stars
Strengths: Those old enough to remember the venerable "film loop" rendition of this problem will appreciate the interactivity of this applet simulation. All relevant physical quantities are clearly displayed.
Concerns: The simulation does not allow the user to follow the wavepacket for very long distances or times. This may inhibit understanding of some of the related physical concepts. The item lacks sufficient discussion of what the expected long term behavior of the gaussian wave packet should be. However, other items within this collection deal with these issues.

Potential Effectiveness as a Teaching Tool

Rating: 5 stars
Strengths: Recommended Uses for Material: Lecture/Demo & Tutorial


The applet allows four available barrier heights that illustrate the relevant physical principles very well. There is a bit of textual explanation that is clear and concise.


This is a very well done applet that illustrates several core ideas in elementary quantum mechanics, including tunneling and propagation into the classically forbidden region. The use of physical units corresponding to a real physical system avoids the abstractness of normalized units. Will be most effective when used as a component in conjunction with the rest of this Meta Site.

Concerns: The wavepacket on the left does not "appear" to spread in the the time viewed. The long time asymptotic results can be important, but are not clearly displayed, indicated or discussed.

Ease of Use for Both Students and Faculty

Rating: 5 stars
Strengths: The applet is very well organized and is very aesthetically done. Intuitive and easy to use.
Concerns:
--%>