- Tin can telephone
A tin can telephone is a type of voice-transmitting device made up of two
tin can s,paper cup s or similar articles attached to either end of a string.Construction
This device can easily be made with two tin cans, or paper or plastic cups, and a length of string. Make sure the cans or cups are empty, clean and dry with no sharp edges. Punch a small hole in the center of the bottom of each can or cup, just large enough for the string to pass through. Insert the string into the hole from the outside, then tie a few knots in the end so the string doesn't slip back through the hole when it's pulled tight or "". Alternatively, the string may be atached to a button.
How it works
Sound waves are created as the air vibrates in response tospeech or other sounds. Theear collects these sound waves and converts them intonerve impulse s which thebrain interprets as sound.When the string is pulled taut and someone speaks into one of the cans, its bottom acts as a diaphragm, converting the sound waves into mechanical back-and-forth motions which vary the
tension (or "tautness") of the string. These variations in tension set up waves in the string which travel to the other can, causing its bottom to vibrate in a similar manner as the first can, thus recreating the sound.History
In the centuries before tin cans and paper cups became commonplace, other cups were used and the device was sometimes called the "lovers' telephone". During the 20th century, it came into common use in preschools and elementary schools to teach children about sound vibration. Fact|date=April 2008
References
External links
* [http://www.dsokids.com/2001/dso.asp?PageID=100 Tin Can Telephone]
* [http://www.wikihow.com/Make-a-Play-Telephone How to Make a Tin Can Telehone]
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