This example problem demonstrates how to find the energy of a photon from its frequency.
The red light from a helium-neon laser has a frequency of 4.74 x 1014 Hz. What is the energy of one photon?
E = hν where
E = energy
h = Planck's constant = 6.626 x 10-34 J·s
ν = frequency
E = hν
E = 6.626 x 10-34 J·s x 4.74 x 1014 Hz
E = 3.14 x -19 J
The energy of a single photon of red light from a helium-neon laser is 3.14 x -19 J.