How lobsters make sounds
Beats: the superposition of waves of slightly different frequency.
Standing waves: the superposition of two waves travelling in opposite directions.
Doppler effect: moving source.
Thomas Young's double slit experiment
Schaum Outline: Physics for Engineering and Science
Action potentials turned into pulses of sound
Maxwell in the Economist.Wikipedia on polarization
Images for birefringence
Cosmic microwave background radiation-->
An electrostatics puzzle