Here's a demo that shows the nearly sinusoidal waveforms produced by two clay whistles.

Here are four movies showing rotating phasors and how the real part of the phasor traces out a sinusoid versus time. Two of the movies show how rotating phasors of different frequencies interact to produce complicated waveforms such as beat signals.

Sine Drill (sindrill) is a program that tests the users ability to determine basic parameters of a sinusoid. After a plot of a sinusoid is displayed, the user must correctly guess its amplitude, frequency, and phase.

This is an introduction to plotting sinusoids (both sine and cosine waves) from equations. The tutorial also reviews how to write the equation of the sinusoid given a plot of the waveform.

This demo shows how the size and stiffness of a tuning fork affect the tone produced by three different tuning forks.

ZDrill is a program that tests the users ability to calculate the result of simple operations on complex numbers. The program emphasizes the vectorial view of a complex number. The following six operations are supported:

• Add
• Subtract
• Multiply
• Divide
• Inverse
• Conjugate