500 6D20.55 two dimensional grating L-79 View an automobile headlamp through a small square of silk. Winner of the 1973 AAPT apparatus competition. L-80 Look through a drop of blood on a microscope slide at a point source or project onto a screen from a point source. Dust a bathroom mirror and hold a small light as close to the eye as possible. A collimated beam of white light is passed through a glass dusted with lycopodium powder giving a maximum at 50 cm with a 60' throw.
Light is diffracted by ultrasonic waves in a liquid.
The sparkling of a spot illuminated by a laser beam on the wall is caused by random interference patterns caused by scattered light. The patterns disappear as the object is brought closer to the arc. Train yourself to see them.