Education Technology

Holt Physics: Brightness of Light

Published on 01/18/2009

Activity Overview

This probeware version of the Skills Practice Lab Brightness of Light from the chapter Light and Reflection uses a light probe to measure the intensity of light at different distances from a light source.

Before the Activity

Read the entire lab (Teacher Resources PDF file) and plan what steps you will take.
Make copies of the Student Activity PDF file for your class.
Make sure DataMate is on all student calculators.

During the Activity

Students will:

  • Find the relationship between the intensity of the light emitted by a light source and the distance from the source.
  • Explore the inverse square law in terms of the intensity of light


  • Directions:
  • Distribute the student activity sheets
  • Follow the procedures as outlined
  • After the Activity

    After the experiment students will:

  • Use their results to investigate the relationship between the distance and the brightness of a light source and to examine the inverse-square law as it relates to the brightness of light
  • Use their data to calculate the square of the distance
  • Analyze the relationship using graphs of their data
  • As a class, review student answers, discussing problems that appeared to be more challenging, and reteaching as needed.