Question

How do we measure frequency of electromagnetic wave?

Answer 1

=The Frequency of an EM wave is measure in exactly the same way as the frequency of say a sound wave or an set of ocean wave. It is measured in Hz (Hertz) which is literally a count per second: Given a traveling wave how many waves pass a given fixed point in one second.✔✔

Answer 2

Hey mate here is your answer☺

Divide the velocity of the wave, V, by the wavelength converted into meters, λ, in order to find the frequency, f. Write your answer. After completing the previous step, you will have completed your calculation for thefrequency of the wave. Write your answer in Hertz, Hz, which is the unit for frequency.

Electromagnetic waves are categorized according to their frequency f or, equivalently, according to their wavelength λ = c/f. Visible light has a wavelength range from ~400 nm to ~700 nm. Violet light has a wavelength of ~400 nm, and a frequency of ~7.5*1014 Hz.