Heat-savers
What kinds of materials can be used to slow down heat? You can use your
refrigerator to make an easy test.
Make sure there is enough room in the bottom of the freezing compartment
in your refrigerator to hold the materials you test.
Cut a small square from the aluminum foil and the paper, and a piece
about the same size from the plastic foam cup. Now you are ready to make
the test.
Place these pieces, as well as the marble, penny, quarter, and wooden
button, in the freezing compartment. Make sure that they do not touch
each other. Close the refrigerator door and wait five minutes.
Open the refrigerator and lightly touch each thing with a different
finger. Which ones feel coldest?
The aluminum foil, the penny, and the quarter will feel coldest. Because
they are metal, they are good conductors of heat. So they lose heat
quickly in the cold freezing compartment.
The glass marble will not feel as cold as the metal things. And the
paper, the wooden button, and the plastic foam will hardly feel cold at
all. Glass, wood, paper, and plastic foam are poor conductors, so they
are good insulators. They can be used to slow down the movement of heat.
