How do you calculate the frequency of light if you know its wavelength?

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Answer 1 · 2016-02-15T12:16:33

For light:

frequency = #c / lambda#

speed of propagation of a wave = wavelength x frequency
speed of propagation of light in a vacuum = #c ~= 3 times 10^8 ms^-1#

Rearranging to make frequency the subject:

frequency = speed of propagation of light / wavelength

The symbol for wavelength is lambda, #lambda#.

Thus for light:

frequency = #c / lambda#

Note that if light is travelling through something other than a vacuum (e.g. glass) its speed of propagation will be altered.