Can the wavelength of light change?

1 Answer
Feb 21, 2016

Yes! When it goes from one medium to another its wavelength and speed will change.


The speed (#v#), wavelength (#\lambda#) and frequency (#f#) of sinusoidal waves are related to each other as : #v=f.\lambda#

Light is a sinusoidal electromagnetic-wave to which the above relation applies. Speed of EM Waves depend on the electric and magnetic properties of the medium. When light goes from one medium to another its speed changes because of the change in electro-magnetic properties of the medium.

The frequency of EM Waves depend only on the source that is generating it. So frequency cannot change and remains a constant. So if the speed change then the wavelength must change proportionally to keep the frequency a constant.

When light goes from a rarer medium (say air) to a denser medium (say water) its speed decreases. To keep the frequency as a constant, its wavelength would decrease too.