* Tuning Fork Fun
This is a simple, very fun, inexpensive experiment that highlights the important scientific principle of sound vibrations. Sounds typically travel freely through the air, but this experiment uses a unique method to direct the sound vibrations directly to your ears. It also lets your child create a very cool bell tone that is done using only a piece of string and a common eating utensil!
* What you’ll need for this experiment:
A piece of string about 3-4 feet (about 1 meter) in length
A metal fork
A few different hard surfaces to experiment with (a wall, a piece of wood, a piece of metal, etc.)
* Step One: Lay out your long piece of string on a table, or other flat surface. Give yourself enough room so that you can lay the string out flat, and easily find the center point.
*Step Two: Place the fork in the middle of the string so that the handle is laying across the string.
*Step Three: Now tie the string tightly around the fork so that you have a pretty even length of string on either side of the fork handle. You should now have a fork with about a foot and a half or so (about half a meter or so) of string on either side of it.
*Step Four: Wrap and tie one end of the string around your forefinger (your pointer finger). Now wrap and tie the other end of the string around your other forefinger. It should now look like you have a big “Y” made out of string, with the fork dangling at the bottom from its handle.
*Step Five: Put your fingertips in your ears (like you are plugging your ears), and let the fork strike the wall or some other hard object. If the string is stretched tightly as the fork strikes a hard object, you’ll hear what sounds like the ringing of a bell! Try striking the fork on different surfaces. Does the sound change? Does the fork hitting a metal object sound different than the fork hitting a wooden object?
*Why does this experiment work?
When the metal fork strikes a hard object, it turns into a tuning fork, allowing sound vibrations to travel straight to your ears. Usually, sound vibrations are carried through the air waves, which is why a sound can often be heard from relatively far away from the source of the noise. However, in this case, the sound vibrations are carried through the string that is wrapped around your fingers and the fork handle. The fingers then direct the sound vibrations from the string to your eardrums, allowing you to hear the sound of bells.