LEsson 2

Wave Properties and Medium

Using PhET Wave on a string

Navigate to PhET's Wave on a String Simulation. https://phet.colorado.edu/sims/html/wave-on-a-string/latest/wave-on-a-string_en.html
On the right side of the screen, select "No End."
Ask students for input. Try making wave disturbances manually. Try making them with wave pulses. Try oscillations. Play with the settings for about three minutes.
Reset settings, still choosing the "No End". Start a pulse. "Notice the green circles. What will the motion of the 4th green circle be as the wave approaches? Once the wave reaches it, will it move up or down?"
As the wave reaches the crest, pause the simulation. "What will the motion of the 4th green circle be at the top of the wave? In the next moment, will it move up or down?
Use the step forward button to slowly step forward.

Wave FlipBook

This activity will take about 30 minutes.
In 15-20 post-it notes, show snapshots on each note of a traveling wave.
The wave should include at least one crest and one trough. It does not have to be a periodic wave.
Instead of a green dot, include a "particle" in your drawing that the wave passes through.
Be sure to show change your particle's position as the wave passes.
Show video below to demonstrate a flipbook to students.

Wave Machine Lab

Purpose: This lab shows how a wave will change speed as it changes medium. It also shows how the wavelength will change.

Materials: metersticks, stopwatches, straws, masking tape, and play-doh.
Optional substitute materials: BBQ skewers and dots candy. If you wanted to use candy (like dots) instead of play-doh, that will also work well with the straws and all pieces are already standardized.

Tips: Have up to four students at a time help build it with you!

Create the straw wave machine:

Carefully roll out the tape. Recommended length is 1-2 meters. A two-meter length is a nice length if you have the space.
Place tape sticky side up securely between desks or partitions.

Place straws on top of the tape. If you'd like to be precise, you can mark the center of the straws. Some twisting of the tape might occur. Don't spend too much time on this part. The videos below show using straws and how you could build the machine using skewers.

PXL_20230418_164324841.mp4

PXL_20220926_174039386.mp4

Demonstrate the wave machine.

If comfortable, allow students to come up and demonstrate and make observations.

Have students answer the questions.

PXL_20230418_182846002.TS.mp4

Divide modeling dough into equal amounts. Each 1-oz container can be broken up into eight pieces.

Add the modeling dough to half the wave machine.

PXL_20230418_165320632.mp4

Demonstrate the wave machine. If comfortable, allow students to come up, demonstrate, and make observations.
Have students answer the questions. Ask leading questions to get students to observe the change in speed and wavelength.

PXL_20230418_183154972.TS.mp4

Sound Wave Mediums

SAFETY: Students could damage their ears if they stick their fingers in their ears or hit the hanger with too much force. Make sure to keep students safe from harmful behavior.

Students should place index fingers (with hanger assembly attached) gently on the small flap of skin just in front of their ears, closing off the ear canal without putting their fingers or the string into their ears.
Swing the hanger so that it collides gently against something hard, like the edge of a desk, and then let the hanger hang free. As the hanger vibrates, you should hear the resulting sound ring through the strings like chimes.
Try tapping gently on the string or on the hanger with other materials.

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