The Nature of Light

Light is radiation. Radio waves are light. Television waves are light. X-rays are light. Gamma rays are light. Microwaves are light. UV (ultraviolet) light and IR (infrared) light are light. These are all the same phenomenon. The difference is specifically that they are different colors; mostly colors which we cannot see with our eyes (due to size and chemistry). Our eye reacts specifically to light which has the colors which are most prevalent from the sun. (This is hardly a coincidence if you consider that we evolved in an environment awash in light from the sun!) In order to explain the previous section, it must be that the light is not a continuous stream. The light must come in VERY tiny bundles (photons). Each bundle has a specific amount of energy. The color of light (the frequency) is related to the energy in a single bundle of that light. Brighter light means more bundles, not bigger bundles. Bigger bundles means a higher frequency of light - different color light. So,

E = hf (5)

where $h = 6.626\times 10^{-34}\,{\rm J \cdot s} = 4.136\times 10^{-15}\,{\rm eV \cdot s}$ is a constant, f is the frequency, and E is the energy in a single bundle of the light.