Example 5.5: The Energy of a Photon

Now that we know how to calculate the wavelength and frequency of a photon, we can use this information, along with Planck’s constant, to determine how much energy each photon carries. How much energy does a red photon of wavelength 630 nm have?

Solution

First, as we learned earlier, we can find the frequency of the photon:

Next, we can use Planck’s constant to determine the energy (remember that a Hz is the same as 1/s):

Check Your Learning

What is the energy of a yellow photon with a frequency of 5.5 × 10¹⁴ Hz?

Answer:

Bibliography

This example is a derivative work of the Creative Commons source in [1].

[1] Andrew Fraknoi, David Morrison, and Sidney Wolff, “Example 5.5: The Energy of a Photon,” in “5.4 The Structure of the Atom,” Astronomy 2e. Houston, Texas: OpenStax, 2022. Licensed CC BY 4.0 in the original 2022 release (https://creativecommons.org/licenses/by/4.0/). Changes: converted to LaTeX and separated from its parent section as a standalone PhysicsLibrary example. Access for free at https://openstax.org/books/astronomy-2e/pages/1-introduction. Section source: https://openstax.org/books/astronomy-2e/pages/5-4-the-structure-of-the-atom.