The Corpuscular Theory of Light Newton proposed this theory that treats light as being composed of tiny particles. We use this theory to describe reflection. While the theory can explain the primary and secondary rainbows, it cannot explain the iridescent cloud. The Wave Theory of Light Proposed by Huygens, this theory describes light as waves that spread out from the source that generates the light. Each color is a different wavelength.
Iridescence is explained by assuming that light is a wave.
It is an improvement over the wave theory in that it explains how light is generated. Visible light is only one type of electromagnetic wave. This theory is very math intensive and we won't discuss it in this course. It is similar to the corpuscular theory of Newton, except that instead of describing light as particles, light is composed of 'packets of energy' or photons. The energy of the photon determines the color.