# Lesson Plan: Photon Momentum Physics • 9th Grade

This lesson plan includes the objectives, prerequisites, and exclusions of the lesson teaching students how to calculate the momentum of a photon given its frequency or wavelength.

#### Objectives

Students will be able to

• recognize that photons have momentum, even though they do not have mass,
• recognize that, for one photon, this momentum is very small,
• recognize that the momentum of a photon is inversely proportional to its wavelength,
• recognize that the momentum of a photon is directly proportional to its frequency,
• use the formula ,
• use the formula ,
• find the total momentum of identical photons, given the wavelength or frequency of each photon.

#### Prerequisites

Students should already be familiar with

• the idea that light can be modeled as a wave,
• terms for the basic properties of waves: frequency, period, wavelength, wave speed, and amplitude,
• how to use the formula ,
• the idea that light travels at a speed in a vacuum, with a value approximately equal to m/s,
• how to represent numbers using scientific notation,
• the idea that light consists of particles called photons.

#### Exclusions

Students will not cover

• compton scattering,
• the de Broglie wavelength of massive particles,