TOPIC:

ID Code: M4-21
Purpose: Very simple and clear demonstration of soap film interference.
Description: A Bright point source of light at the right illuminates a soap film in the wire ring. The transmitted light is seen at the left and the reflected light at the rear between the light source and the wire ring. Note that the reflected and transmitted colors are complements, although the transmitted light is desaturated by the white light background, as seen above.

After a while the top section of the film becomes less than one-quarter wavelength thick, so the waves reflected from the front and rear surfaces of the film are out of phase, resulting in no reflected light.

Availability: Available