On this week’s episode of “For Science!” we explore vibrations and sound waves by creating a mason jar xylophone. Sound waves are created by vibrations which are back-and-forth movements repeated over and over again.
We will also explore pitch which depends on the frequency of the waves meaning how many are created each second.
A high pitch is created by high-frequency sound waves, and can sound squeaky. A low pitch is created by low-frequency sound waves, and sounds deep.
Material List
- 6 Milk Bottles or Mason Jars (any matching glassware typically works)
- A metal spoon
- A measuring cup
- Food coloring (optional for fun)
- Water
Arrange six glass jars or bottles, all the same size with no lids, in a line. Make a prediction on what you believe they will sound like, then tap each jar. Record your observations.
Next, put water in each of the jars.
- Pour 1⁄4 cup of water into the first jar.
- 1⁄2 cup of water to the second jar.
- 3⁄4 cup of water to the third jar.
- 1 cup of water to the fourth jar.
- 1 1⁄4 cups of water to the fifth jar.
- 1 1⁄2 cups to the sixth jar.
Add a couple of drops of food coloring to each jar if you would like to at this time.
Record your predictions on what you believe each jar will sound like on a piece of paper.
Tap each jar with a metal spoon. Write down your observations about each jar’s pitch.
When you tapped the jar, it vibrated and those vibrations traveled from the jar to the water to the air and eventually to your ears. The jars with more water had a lower pitch. The sound waves vibrated more slowly because they had more liquid to travel through. A jar with no liquid in it makes the highest pitch because it has the least substance to travel through before moving to your ears.