Waves of Energy
RETIRED BETA VERSION - For current versions of the SciGen materials, please visit serpmedia.org/scigen
Set up stations where your students can interact and play with sound in several different ways. There are nine suggestions below, and each can take about 5 minutes. You can set up as many as you'd like, or just pick one activity for everyone to try as a class. Each activity has PDFs of printable pages for the station's suggestions/instructions and recommended discussion questions.
The starred (*) activities were developed in cooperation with Kate Maher of M.S. 20 in the Bronx—thank you!
Scientists and engineers use a tool called an oscilloscope to compare different waves, including sound waves. The "oscillo-" part of the word means "swing", just as in the word "oscillate." Musicians don't usually pay any attention to the shape of the waves, but this special instrument makes sound and then lets you play around with it.
Materials:
Procedure:
Turn and Talk
Answer these questions in your lab book.
Is there a difference between volume and amplitude?
How do the different shapes—square, sawtooth, triangle, and sine—sound different?
Why does the live input of the microphone make such jagged waveforms, while the notes produced by the computer are much more smooth?
Describe the different waves for different pitches for high and low notes.
How does pitch or frequency affect the waveform on an oscilloscope?
How do the curves compare for keys whose frequencies are 440 and 220 Hz?
How do the sounds compare when the same note is played as a sine, square, or triangle waveform?
The human body is equipped to make and sense sound vibrations. While we think of our ears as organs of hearing, the fine hairs are actually very tiny touch sensors that sense movement in the fluid of the cochlea, the curled canal inside the inner ear. The vocal cords change shape to produce distinct tones that are further shaped and amplified by the throat and mouth. In this activity,
Materials:
Procedure:
Turn and Talk
Answer these questions in your lab book.
What do you feel as you hum?
How did you create different pitches?
YOu can find your pulse in your neck in the vein not too far from your vocal cords. Why do we hear air vibrating the vocal cords but not the pulse amplified?
What's making the sound and how do we hear it? Watch this looping animation. Roll over parts of it to learn more about what's happening. How does the animation describe how the sound waves of the human voice are generated and received? Draw a diagram like this in your lab book.
Sound waves are mechanical waves; they need a medium to transmit energy. When we clap our hands, the air between our hands gets compressed. The air molecules bump into each other, creating a vibration that travels through the air as a longitudinal or compression wave.
Materials:
Preparation:
Procedure:
Turn and Talk
Think about it. How does that work? Answer these questions in your lab book.
Describe the series of different materials that vibrated to make the telephone carry sound.
Which medium conducted sound more effectively- the air in the room or the cups and string? Why?
When you speak into the cup, what type of wave are you creating?
What is the medium that is transmitting the sound wave from your mouth to the bottom of the cup?
What do you think happens when the sound waves reach the bottom of the cup?
How does the sound of your voice travel from your cup to your partner’s cup?
What happens when the sound waves reach your partner’s cup?
Every sound is made when something vibrates. Sometimes it's the skin stretched across a drum, sometimes it's a plucked string. By fine tuning the amount of what is vibrated, you can make notes of different pitches. Students adjust the pitch of a simple musical instrument by changing the amount of freely moving wood that gets plucked.
Materials:
Procedure:
Turn and Talk
Think about it. How does that work? Answer these questions in your lab book.
What happens to sound as you change the length of the ruler that's hanging off the table? What would you predict would happen if 25 or more centimeters were hanging off the edge of the table?
At which length did the stick create the sound with the highest pitch? Why do you think this is?
Compare what you have observed at this station to a musical instrument. Explain your comparison.
Students may be familiar with the pumping beat heard from a passing car, with the bass set so high and the volume so loud that the neighborhood windows shake. This transfer of energy is easy to see with a small boom box and some pepper sprinkled on paper. For a more ambitious demo, consider building a Chladni Plate or at least watching a video of them in action.
Materials:
Procedure:
Turn and Talk
Think about it. What's happening here? Answer these questions in your lab book.
What happened to the balloon as you adjusted the volume?
What happened to the pepper specks as you adjusted the volume?
Did the frequency of the vibrations change as the music changed? In what way?
Every sound is made when something vibrates. Sometimes it's the skin stretched across a drum, sometimes it's a plucked string. By fine tuning the amount of what is vibrated, you can make notes. At this station you'll make a full octave of eight notes.
Materials:
Procedure:
Turn and Talk
Think about it. How does this instrument work? Answer these questions in your lab book.
What happens when you blow across the top of the pipe?
What is vibrating to make the sound waves?
Does a long pipe make a high note or a low one? How about a short pipe?
Every sound is made when something vibrates. Sometimes it's the skin stretched across a drum, sometimes it's a plucked string. BY fine tuning the amount of what is vibrated, you can make notes. At this station you'll make a full octave of eight notes.
Materials:
Procedure:
Turn and Talk
Answer these questions in your lab book.
What is vibrating to make a sound? How is it different in each glass?
What medium is transmitting the sounds waves?
If you figured out a song to play, write its notes down.
Do your best to avoid dropping your tuning forks. They are very easy to break. They are very delicate. Hold them only by the handle, and strike them only against rubber: if you don't have a sounding block, some science teachers and their students have used the sole of their shoe as a striking surface.
Materials:
Preparation:
Procedure:
Turn and Talk
Think about it. How does that work? Answer these questions in your lab book.
What do the numbers on the tuning forks represent? Do the numbers correspond to the size of each fork? Why or why not?
Which tuning fork had the highest pitch? Why do you think that is?
What happened when you touched the tuning fork to the desk?
What happened to the ball after it was touched by the tuning fork? Why do you think that is?
Which tuning fork had the greatest effect on the ball? Why do you think that is?
Resonance boxes and tuning forks make it possible to hear a usually undetectable phenomenon: waves transferring energy from one medium to another. They can be quite expensive, however, and you may be able to demonstrate a similar phenomenon by simply bringing the vibrating end of a tuning fork close to the surface of some water, and touching it to the surface.
Materials:
Procedure:
Turn and Talk
Think about it. What's happening? Answer these questions in your lab book, or use this form.
What happened to the second tuning fork after you struck the first one with the striker? Why?
What happened when you tried this with a weight on one tuning fork? Why?
© SERP 2017
This Science Generation unit is currently in development. If you have comments or corrections, SERP would love to hear from you! Thank you.