This example problem demonstrates how to find the energy of a photon from its frequency.

## Problem:

The red light from a helium-neon laser has a frequency of 4.74 x 10^{14} Hz. What is the energy of one photon?

## Solution:

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 10^{14} Hz

E = 3.14 x ^{-19} J

## Answer:

The energy of a single photon of red light from a helium-neon laser is 3.14 x ^{-19} J.