Education Technology

Lights Out: Periodic Phenomena

Published on 06/18/2010

Activity Overview

In this activity, students will use a light sensor to collect intensity data for fast and slow variations of intensities. They will then describe these variations using the concepts of period and frequency.

Before the Activity

  • Connect the light sensor to Channel 1 on the CBL 2™ or Vernier LabPro®
  • Connect the CBL 2 or LabPro to the calculator using the Unit-to-Unit cable
  • See the attached PDF file for detailed instructions for this activity
  • Print pages 237 - 243 from the attached PDF file for your class
  • During the Activity

    Distribute the pages to your class.

    Follow the Activity procedures:

    Method 1:

  • Point the sensor toward a light source and begin data collection
  • Use the thumb to cover and uncover the light sensor at one-covering-per-second rate
  • Observe the graph of light intensity versus time
  • Determine the period and frequency of the cover-uncover function


  • Method 2:
  • Point the sensor toward a fluorescent light source and recorded intensity every 0.0005 seconds
  • Examine the light intensity versus time plot
  • Determine the period and frequency of the pattern from the fluorescent light
  • Model the data using an absolute value sinusoidal equation
  • calculate the flicker frequency
  • After the Activity

    Students will analyze the data and fill in the Data Collection and Analysis Sheet. They also answer the questions listed in it.

    Review student results

  • As a class, discuss questions that appeared to be more challenging
  • Re-teach concepts as necessary