Thread one end of string through the bottom of each cup. Punch a small hole in center of the bottom of each cup (for plastic cups, you might need a nail or other sharp tool, so use caution when completing this step). Length of cotton string or fishing line approximately 10 to 30 feet long. Two large paper cups (disposable plastic cups will also work). Having a soft connective material, such as cotton string-which has a higher density, or number of molecules in a given amount of space, than air-can help the sound waves move over a greater distance. So sound vibrations tend to peter out before they travel very far. The brain interprets sounds as having different pitches, or tones, based on the frequency, or spacing, of the waves.īut the particles in air are spread out from one another more than particles in a liquid or solid. They pick up the vibrations and transmit that information to our brains, which interpret it as sound. Inside our ears are tiny sensitive hairs. (Different pitches of sound move in waves that have different spacing between them-or "frequency.") Other sources of sound, such as guitar, violin or piano strings are good examples of how vibrations can generate sound. (You can feel the vibrations by holding your hand against your throat while you talk.) Those vibrating air molecules make other air molecules around them vibrate, and so on, which is how sound travels through the air. 
When we talk, our vocal cords make molecules in the air vibrate.
What message are you going to share over the string? And you can use the same concept to build your own telephone using just cups and some string. So these days it's nice to be able to use telephones to talk with someone-whether he or she is 100 yards or 100 miles away.īack before there were cell phones or even cordless phones, all telephones were hooked up to wires that helped to carry the sound of a person's voice (via an electric signal). Have you ever tried to have a conversation with someone so far away that you couldn't really hear each other? Without yelling, it's hard to have a conversation over long distances. If viewing digitally, click on a section at right to jump there.From National Science Education Standards: Transfer of energy
0 kommentar(er)
