A Thermometer

Most thermometers employ the expansion
of a liquid; Mercury or Alcohol. Not this one !

 

Materials:
1. One film canister any cylindrical type
2. Aluminum foil - heavy duty
3. Masking tape
4. 3"x5" index card
5. Scissors

6. Protractor

Directions:
1. Cut a piece of the Aluminum foil the width of the masking tape and 8cm long.
2. Tape a piece of masking tape the entire length of the foil.
3. Trim any excess tape or foil and cut the foil down the center, this will be the pointer.
4. Place the protractor on the White side of the index card perpendicular to the card in a position so the arched part of the protractor is about 0.5 cm from the edge. Trace the curved part of the protractor on the card.
5. remove the cap from the canister, and cut a slit about i cm long down the side of the canister.
6. Place one end of the pointer in the slit so the pointer is perpendicular to the canister. replace the cap.
7. Make a loop of masking tape and place it on the cap.
8. place the cap on the index card and center so the pointer just passes the curved line on the card.
9. Straighten the pointer and mark the card RT (room temperature) where the pointer crosses the line.
10. Place the Thermometer in the freezer and observe in one hour, mark the card FT (freezing temperature) where the pointer crosses the line.
11. Place the thermometer under a lamp for one hour and mark the card HT
(high temperature) where the pointer crosses the line.
12. If you want you can find the precise temperatures for each position and develop your own temperature scale or use one of the present scales.


Why?
As the Pointer gets colder the Aluminum contracts more than the masking tape and pull the pointer to the side with the Aluminum. When the pointer gets warm, the Aluminum expands more than t he masking tape and pushes the pointer away from the side with the Aluminum.

Scientific Concepts:
Solids like Aluminum expand when heated and contract when cooled because the molecules speed up and require more space or slow down and require less space. They will continue to speed up and expand until the molecules are going so fast that the material becomes a liquid or the molecules escape into the air as a gas.

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