A light source emits a beam of photons, each of which has a momentum of
(a) What is the frequency of the photons? (b) To what region of the electromagnetic spectrum do the photons belong?
The momentum of a photon is given by:
where is Plank's constant and the wavelength of the photon.
Frequency and wavelength are connected via the following equation:
where corresponds to the speed of light in vacuum. Use equation (2) to express in terms of the speed of light and the frequency:
Now, put this into (1):
This photon, according to Figure 24.9 in the textbook, lies in the region of the electromagnetic spectrum