Things You'll Need
2-liter soda bottle
2 12-ounce soda cans
Black poster paint
Solar energy is a powerful force that, when harnessed, can heat objects to a surprising degree. A simple experiment in solar heating can show the power of the sun by heating water hot enough to pasteurize it. You can use this quickly made device to teach about solar power to school children or scout troops, or use it as an emergency water heater when camping.
Paint the outside of the soda cans with a layer of black poster paint. Cover the can thoroughly and allow the paint to dry.
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Remove the label from the soda bottle. Cut the top off the bottle about one inch below the bottle shoulder.
Snip two slices, a half inch apart, upward from the bottom edge of the top half of the bottle. This will create a small plastic tab between the two snips. Make three more tabs around the outside of the bottle top.
Cut three pieces of cardboard or poster board, each measuring 12 inches square. Cover each square with foil and tape the foil down so that it is secure. Tape the sides of two squares together so that they are hinged and can be stood up like two walls in a room.
Lay the third foil-covered square on top of a flat surface in a sunny area. Fill both cans with water. Place the bottom of the water bottle in the middle of the cardboard square. Stack the filled cans, one on top of the other, in the center of the water bottle bottom.
Fit the top of the bottle onto the bottom by slipping the tabs onto the bottle bottom edge. Stand up the two taped squares so that they resemble two adjoining walls around a foil floor. Allow the water to heat until it reaches the desired temperature.