Jack's Page: Basic Physics and Optics

Author: Jack Ord     email: jackord@kw.igs.net

What It Is About

It's all physics, and all of the illustrations (except for eight screen images and the sailing picture on the Entry Page) are produced by Java Applets running in your web browser. If you see an Applet Viewer screen image but no Applet "slide show" on the Entry Page then your browser does not run Java Applets. Most computer browsers can, and a free download is available from Java. Java 8 will require you to find the Java Control Panel, select the security tab, click on Edit Exception Site List, and add http://kw.igs.net. Most mobile device browsers cannot run Java Applets, and that situation is unlikely to change. A Screen Image Gallery has been added to give people with web browsers that do not run Java a rough idea of what is in the Basic Physics section.

Basic Physics deals with simple algorithms for numerical solution of problems in physics, notably Richard Feynman's algorithm for Newton's Second Law. The systems studied begin with a mass oscillating on a spring, and end with a wavefunction oscillating in a harmonic potential well. The final applet in Basic Physics brings the two together. By default the Schrodinger Equation is solved directly and the probability density is plotted. Options enable the time dependence to be generated from the superposition of a series of stationary states, and the plot to show Yr and Yi, the variables in the Schrodinger Equation. An Applet Viewer screen image is shown below the Java Applet.

Basic Physics is aimed at people who want to write their own programs. Java source code is provided for all of the applets along with Liberty BASIC and/or BBC BASIC program listings. PostScript code is included also for some that do not require user interaction. (PostScript runs in the Ghostscript graphical interface GSview).

Optics is divided into Matrix Ray Optics, Matrix Wave Optics, and Ellipsometry (matrix wave optics applied to the reflection of polarized light from film-covered surfaces).

There is also a brief section on transients that shows examples of how a computer can be used acquire and analyze data.

The level of the material and the form in which it is presented are both rather uneven. The early Basic Physics material was aimed at students in a freshman course. The more recent material, aimed at surfers scanning the net for items of interest, is more varied in level and has less decriptive detail. The level of the Optics material increases progressively the farther one goes into it.

Index and Program Directory

Basic Physics

Basic Physics introduces algorithms for "back-of-the-envelope" calculations in physics. It takes its name partly from the BASIC language, and originates from Richard Feynman's algorithm for solving F = ma problems on 1960-vintage calculators. The algorithms are simple, but accurate, and can be applied to a wide variety of problems in physics.

Newton's Law and the Feynman Algorithm

Fieldlines, Equipotentials, and Colour Potential Plots

Energy Conservation and Integration

The Special Theory of Relativity

Wave Motion

Matrix Ray Optics: Matrix Optics by Ian Dagg, Web Edition by Don De Smet

Matrix Wave Optics

A matrix treatment of wave propagation that continues on from the matrix treatment of geometrical optics and provides the groundwork for the sections on ellipsometry.



A brief self-contained introduction to the subject. A more detailed discussion of the introductory material is given in the Matrix Ray Optics and Matrix Wave Optics sections. A more general discussion of ellipsometry, including the Jones Calculus description of polarized light, can be found in A Closer Look at Nulling Ellipsometry by Don De Smet. Detail on the operation of a typical null instrument can be found in Principles of Operation of the Exacta 2000, also by Don De Smet.


Programs for the analysis of exponential and logarithmic transients. The 'capacitor tester' program is from an interfacing exercise for graduate students (or demonstration for freshmen). The logarithmic transient program is used in research on high-field ionic conduction. Both programs use data acquired under program control by interface hardware that sets the current through and reads the potential across an external circuit.

PostScript File Directory