|MLA Citation:||Bloomfield, Louis A. "Question 1083"|
How Everything Works 17 Jan 2018. 17 Jan 2018 <http://howeverythingworks.org/print1.php?QNum=1083>.
However, something has happened—the light wave has been delayed ever so slightly. This absorption and reemission process holds the light wave back so that it travels at less than its full speed. If the charged particles in the matter are few and far between, this slowing effect is almost insignificant. But in dense materials such as glass or diamond, the light wave can be slowed substantially.
Actually, higher frequency violet light is slowed more than lower frequency red light because violet light is more effectively absorbed and reemitted by the atoms in most transparent materials. That's because when a high frequency light wave encounters the electrons in an atom, the jiggling motion is so rapid and the electrons' motions are so small that the electrons never reach the boundaries of the atom. As a result, those electrons are able to jiggle back and forth as though they were free electrons and they do a good job of slowing the light wave down. But when a low frequency light wave encounters the electrons in an atom, the jiggling motion is slower and the electrons' motions are so large that they quickly reach the boundaries of the atom. As a result, those electrons aren't able to jiggle back and forth as far as they should and they don't slow the light wave down as well.