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In this classic activity, make a record player out of simple materials and listen to your favorite vinyl LP—no outlet required.
Make the turntable:
Make the needle arm and sound cone:
This activity requires two people: one to rotate the turntable and one to hold the needle arm and sound cone.
To set up the turntable, hold the pencil-and-record assembly on a tabletop, point-side down, like a spinning top (the pencil will act as the axle of your spinning top). Make sure the record stays as horizontal as possible. Gently twirl the pencil, turning the record clockwise. See if you can spin the record at 33 1/3 revolutions per minute (RPM)—good luck!
To set up the needle arm, grasp the wider end of the sound cone and bring the pointed end of the cone (with the pin hanging down) close to the record. Orient the needle arm so the pin is parallel to the groove and the cone lies tangent to the record. (To get a consistent sound, the pin needs to rest comfortably in the groove as the record rotates beneath it. Click to enlarge the image below.)
When you're ready, slowly lower the pin so that it rests in a groove of the spinning record. Gently hold just the top of the cone and let the weight of the cone be supported by the pin, allowing it to move with the motion of the spinning record.
Listen to what comes out of the open end of the paper cone. It should be music to your ears!
Your record has a groove in it. The groove is not smooth; rather, it has microscopic bumps and bends that correspond to the recorded music (click to enlarge image below).
As the record turns, the tip of the pin travels within the spiraling groove, riding these bumps and bends and causing the pin—and therefore the paper cone—to vibrate up and down and side to side.
The vibrations in the cone cause the air to vibrate. These vibrations then radiate out from the cone to your ear, which you hear as music, voices, or whatever has been recorded on the record.
This Snack lends itself well to engineering and design challenges. Here are a few ideas:
Inexpensive old records can be found at thrift shops, garage sales, and record stores. Have a variety of materials and records on hand for experimentation!
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Attribution: Exploratorium Teacher Institute