# Does wavelength of light change in different mediums?

Jan 6, 2016

Yes, the wavelength shortens as it passes through an optically dense medium.

#### Explanation:

Physicists refer to light as electromagnetic waves, referring to the fact that light is made up of two oscillating fields; one is magnetic, and the other is electric.

Light travels fastest in a vacuum. When the light encounters a medium, such as glass, the charged particles that make up the glass interfere, slowing the wave down. The wave continues to oscillate at the same rate, however, so as the wave slows, the wavelength must contract.

In the image above, $N$ refers to the index of refraction, or the ratio of the speed of light in a vacuum to the speed of light in the material. $N = 2.0$ means that the speed of light has decreased by half inside of the medium.

$N = \left(\text{speed of light in a vacuum")/("speed of light in medium}\right)$