Why were the first lightbulbs (I assume from vague general knowledge) yellow and what property changes inside lightbulbs so that we can have blue, green or red colours.
In: Physics
There are different colors because people will buy different colors. In the bad old days, colored light bulbs had a filter material painted on the inside of the glass to absorb all the colors except the desired one. This made them less energy efficient than ordinary incandescent bulbs, no mean feat.
Today most colored bulbs are LED, where they simply put LEDs inside that make the desired color.
Latest Answers