A rocking chair moving back and forth, a ringing telephone, and water dripping from a leaky faucet are all examples of periodic phenomena. That means that the phenomenon repeats itself every so often. The period is the time required to complete one cycle of the phenomenon. The number of times the cycle occurs per unit time is known as the frequency.

In the following activities, you will use a Light Sensor to collect data for two different types of periodic phenomena. You will then analyze this data with the calculator to find the period and the frequency of the observed behavior.


  • Record light intensity versus time data for both fast and slow variations of intensity.
  • Describe the intensity variations using the concepts of period and frequency.