Iridescent colors, which change the appearance with the angle of viewing and the direction of the illumination, are due to interference. The delicate hues of soap bubbles and oil films, the pale tints of mother-of-pearl, and the brilliant colors of a peacock's tail are all iridescent colors . . . . A soap bubble appears iridescent under white light when the thickness of the bubble is of the order of a wavelength of light. This occurs because light waves reflected from front and back surfaces of the film travel different distances. A difference in phase results that may cause destructive interference for some particular wavelength, and the hue or color associated with that wavelength will be absent from the reflected light. If the missing hue is red, reflected light appears blue-green, the complement of red. If film thickness or direction of illumination changes, interference occurs at different wavelengths and the reflected light changes color.
[pg. 49] [Light and Color, by Clarence Rainwater, Prof. of Physics, San Francisco State College, Original Project Editor Herbert S. Zim, Golden Press, NY, Western Publishing Company, Inc., 1971.]
R E F E R E N C E S
Iridescence n [1804] 1: a lustrous rainbowlike play of color caused by differential refraction of light waves [as from an oil slick, soap bubble, or fish scales] that trends to change as the angle of view changes 2: a lustrous or attractive quality or effect [the agglomeration of power which . . . give them a certain __ of glamor and superiority -Margaret Landon]
Irridescent adj [1791]: having or exhibiting iridescence
irid- or irido comb form 1 [L irid-, iris]: rainbow [iridescent] 2 [NL irid-, iris] iris of the eye [iridology]
[Merriam-Webster's Collegiate Dictionary, 10th Edition. Springfield, MA, USA: Merriam-Webster, Inc. 1995.]
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