How does one measure frequency of the light?

Hint :Light or light is an electromagnetic wave within the portion of the spectrum which will be perceived by the human eye. light is typically defined as having wavelengths within the range of 400–700 nm, between the infrared and therefore the ultraviolet.

Complete Step By Step Answer:
Once you've got a wavelength and therefore the speed, which Michelson also determined to a high degree of accuracy by refining the rotating mirror method, the frequency is simply f=velocity/wavelength. The frequencies are crazy big numbers just like the red during a helium-neon laser is $4.7376 x 10^14$ per second or 473.76 THz.
Frequency is more complicated, because the frequency of light is within the range of many THz. There are two basic tricks. First, you'll measure the difference in frequency between two oscillators by adding the signals and measuring the much lower “beat frequency” Interference and Beats, a way called heterodyning.
If one among the 2 frequencies is understood , that bootstraps you to the opposite . Second, if you've got a sign of known frequency, you'll create exact integral multiples of it in non-linear media.

Note :
Usually frequency is measured within the hertz unit, named in honor of the 19th-century German physicist Heinrich Rudolf Hertz. The hertz measurement, abbreviated Hz, is the number of waves that travel by per second. for instance , an "A" note on a violin string vibrates at about 440 Hz (440 vibrations per second).