demonstrations:cornstarch_dancing_on_speaker
Cornstarch Dancing on a Speaker
Materials: ★★☆ Available in most school laboratories or specialist stores
Difficulty: ★☆☆ Can be easily done by most teenagers
Safety: ★☆☆ Minimal safety procedures required
Categories: Sound
Alternative titles: Dancing Oobleck
Summary
A mixture of cornstarch and water, known as oobleck, is placed on top of a speaker. When sound waves vibrate the speaker cone, the non-Newtonian fluid forms strange, moving shapes, making sound waves visible.
Procedure
- Mix cornstarch and water in a bowl, adding small amounts until the mixture has the consistency of honey.
- Test the mixture: it should act like a solid when squeezed but flow like a liquid when left alone.
- Lay the speaker on its back so the cone faces upward and cover it with thin plastic (trash bag or plastic wrap).
- Pour the cornstarch mixture onto the plastic over the speaker cone.
- Connect the speaker to a sound system and select a track or tone generator with a steady bassline or low-frequency tone.
- Play the sound and gradually increase the volume. Watch the oobleck vibrate and form moving “monsters.”
Links
Cornstarch And Water On A Speaker (UV) - Andy Elliott Craft & Creations:
Corn Starch and Water dancing in a speaker - Ontario Traffic Man:
📄 Cornstarch Monsters – Vibrating Cornstarch on a Speaker - Steve Spangler: https://stevespangler.com/experiments/cornstarch-monsters/
Variations
- Test different frequencies to see which produce the most motion.
- Change the volume level to observe how intensity affects the movement.
- Try different ratios of cornstarch to water to see how mixture thickness affects results.
- Use a tone generator app to test exact frequencies (e.g., 20 Hz, 50 Hz, 100 Hz).
Safety Precautions
- Protect the speaker with plastic wrap to prevent liquid damage.
- Cover the surrounding area with newspaper or a drip cloth to control mess.
- Keep liquids away from electrical connections to avoid short circuits or shocks.
- Do not play sounds at excessively high volume.
Questions to Consider
- Why do low-frequency sounds make the oobleck move more than high-frequency sounds? (Low frequencies cause larger speaker cone movements, which push the mixture more effectively.)
- What happens if you change the ratio of cornstarch to water? (The thickness changes, affecting how the mixture responds to vibration.)
- Is oobleck a solid, liquid, or something else? (It is a non-Newtonian fluid—its behavior changes depending on force applied.)
- How does this demonstration help us understand sound waves? (It makes vibrations visible by transferring them into motion of a fluid.)