An energy source heats a liquid by agitating its molecules. That’s how we use electricity to heat water for our mug of morning coffee. The sun also heats water in a swimming pool, or a pond on a clear, sunny day. But the rate it does so depends on the thermal efficiency factors applying. Let’s conduct a simple solar energy experiment to illustrate this point!
Stuff You Need for This Solar Energy Experiment
MATERIALS
- A styrofoam insulation panel four feet long
- One full roll of kitchen aluminum foil
- A roll of scotch or electrician’s tape
- One two-liter plastic liquid container
- A supply of ordinary water on tap
- Three heavy-duty two-liter-plus plastic bags
NOTE: You will need 1 white bag, 1 black bag, and 1 bag of another color
TOOLS
- One pair of sharp kitchen scissors
- Three 10” partial immersion thermometers
- A stopwatch or smartwatch with timer
- Pen and paper to note observations
The Experiment Itself – What You Do
Do your work during the hottest hours of a clear, sunny day. Attach kitchen aluminum foil to one large side of the styrofoam insulation panel with scotch or electrician’s tape. Now take each plastic garbage bag, and cut a very small hole across one bottom corner.
Slide one partial immersion thermometer into each of these holes up to the water-level mark on the device. Secure it tightly with the scotch or electrician’s tape so the joint is watertight. You are now ready to do the solar energy experiment!
Place the styrofoam insulation panel in a sunny place with the kitchen aluminum foil side facing up. Pour two liters of cool water into each of the three plastic bags. Gently place these side-by side on the foil-covered sheet. Note the temperature reading on each partial immersion thermometer.
Start the stopwatch, or the smartwatch with timer. Take regular readings every fifteen minutes, as the heat of the sun agitates the water molecules and warms the water. You will notice temperature differences emerging between the bags. Which color bags are more thermally efficient? What do you think is behind this phenomenon?
More Information
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Two Experiments to Plot a Magnetic Field
