Non-Newtonian fluids exhibit the qualities of both a liquid and a solid. Cornstarch, a thickening agent derived from corn, becomes a non-Newtonian liquid when mixed with water. Several experiments serve to illustrate the strange effects of stress on these types of fluids, among them the cornstarch and speaker cone experiment. Relatively easy to conduct, this experiment illustrates the varying states of cornstarch when irritated by the sound waves produced by a speaker. Simple and fun to observe, this experiment is an ideal activity for science classrooms and may be carried out with very few ingredients.
- 1 box of cornstarch
- 1 cup water
- Old speaker
- Computer or stereo
- 3.5-inch audio adapter cable (optional)
- Plastic bag
Mix the box of cornstarch with 1 cup of water in a bowl. The cornstarch will become difficult to stir, given its properties. Use your fingers to break up any clumps and stir the mixture until it is like syrup in texture.
Remove the speaker cone from the outer housing on the speaker using the screwdriver. The speaker housing should be held together by a series of simple screws. Once you remove the housing, the interior cone may be lifted from the housing without difficulty. Ensure that the speaker wire is still intact.
Connect the end of the speaker wire to a 3.5-inch audio adapter, if necessary. Depending on the speaker you’re using, it may already be equipped with a 3.5-inch audio plug.
Place the speaker cone into a plastic bag to prevent the cone from being damaged. Seal the bag around the cone, ensuring that the connecting wire protrudes from the bag.
Connect the speaker via the 3.5-inch audio plug or adapter, if any, to the “audio out” socket of your computer or stereo. Turn the computer or stereo on.
Pour the cornstarch mixture onto the plastic-covered speaker cone so that the mixture rests in the bowl of the speaker cone. Play different songs on the stereo or computer, experimenting with songs with louder bass sounds. The vibrations in the speaker will cause the cornstarch to jump into the air and tremble, forming tendrils and waves in the cornstarch as it changes from solid to liquid and back again.
Things You'll Need
- “Physics I for Dummies”; Steven Holzner; 2011
- Jupiterimages/Goodshoot/Getty Images