Name That Frequency

Target Subject: Physical Science

Purpose

To model how vibrating particles, such as in a sound wave, bump into other particles causing them to vibrate and that the vibrations travel; to demonstrate the chain reaction of sound waves, using old video cassettes.

Background information

Frequency is the number of complete waves passing a given point in a given time. Wave models show the crests of the wave closer together to indicate higher frequency, and movement of the waves to show the traveling of the vibrations. Phenomenon such as the vibration of particles is frequently modeled using diagrams or pictures.

This activity provides an auditory and tactile experience to model something that no one can actually see. Many people use a row of dominos to show the passage of the vibrations. However, it is difficult to set up the small dominoes without knocking over the adjacent ones.

Preparation

Create or obtain tactile diagrams of varying wave frequencies. Set up the row of tapes at various “frequencies”, closer together for higher frequency, farther apart for lower.

Materials

• Video tapes at least 25
• Wave diagrams
• Timer

Procedure

1. Tactually examine the set up tapes.
2. Observe what happens if the first tape is pushed, then hits the second tape, which then hits the third until all the tapes have been knocked over by the initial vibration traveling along the “wave”.
3. Tactually examine a row of tapes placed further apart from one another.
4. Push the first tape and time with a precise timer, stopping the timer when the sound stops. .
5. Set up the tapes very close together. Push the first tape, and time as above.
6. Compare the times