How can a light bulb produce different colours of light?
In: Physics
The question is a bit complicated to answer so this may not be ELI5.
First: What humans PERCEIVE as color is not necessarily what is being produced by a light bulb. The human eye has 3 kinds of receptors that are sensitive to red, green and blue frequency light waves. Light entering the eye stimulates these receptors by varying amounts. The brain interprets these different level of stimulation as a particular “color”. For example: the color we see as “magenta” actually does not “exist” in the sense that there is no light frequency that is “magenta”. Magenta is perceived when we have blue and red combined. (Blue and red light frequencies are on opposite ends of the visible light spectrum)
Second: A light designed to produce different colors may have more than a single light emitting device. Basically by doing the reverse of what our eyes and brains do, it can fool the brain into thinking it is seeing a spectrum of colors.
Third: some lights are designed to emit different colored lights of a single frequency range. These can either be through the selection of the right metals or gases (the explanation is DEFINITELY NOT ELI5) or by passing the light emitted through filters or phosphors which will modify the frequencies that are emitted from the light source. Filters generally just block some light frequencies (therefore changing the perceived color) while phosphors will absorb light energy of a certain color and emit light of another color.
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