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

  1. Mix cornstarch and water in a bowl, adding small amounts until the mixture has the consistency of honey.
  2. Test the mixture: it should act like a solid when squeezed but flow like a liquid when left alone.
  3. Lay the speaker on its back so the cone faces upward and cover it with thin plastic (trash bag or plastic wrap).
  4. Pour the cornstarch mixture onto the plastic over the speaker cone.
  5. Connect the speaker to a sound system and select a track or tone generator with a steady bassline or low-frequency tone.
  6. Play the sound and gradually increase the volume. Watch the oobleck vibrate and form moving “monsters.”

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.)