Does a black surface trap more of the sun's energy than a white one? Dark colors absorb sunlight while light colors reflect it. This project shows the difference using two plastic bottles and a pair of balloons.
You paint one bottle black and one bottle white. Then you stretch a small balloon over the mouth of each bottle to form an airtight seal. Place both bottles in bright sunlight and watch what happens.
Within minutes the balloon on the black bottle begins to inflate. The air inside warms and expands. The balloon on the white bottle stays flat because the white surface reflects most of the sun's energy away.
Hypothesis
The hypothesis is that the black bottle will absorb the sun's energy better than the white bottle.
Dark colors absorb sunlight while light colors reflect it — and you can see this difference in real time. You paint one bottle black and one white, stretch a small balloon over the mouth of each, and place both in bright sunlight. Within minutes the balloon on the black bottle begins to inflate as the absorbed energy warms the air inside, while the white bottle's balloon stays flat.
When a black bottle absorbs the sun's energy, the air inside warms and the tiny particles in it speed up. Those faster-moving particles push outward with more force, and within minutes the balloon on the black bottle begins to inflate. The white bottle's balloon stays flat because the white surface reflects most of the sun's energy away.
Method & Materials
You will paint two plastic bottles, one black and one white. Place a small balloon on the mouth of each bottle and put them in the sun.
You will need two plastic bottles, paint, and several small balloons.
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The experiment showed that the black bottle absorbed the sun's energy better than the white bottle. The black bottle was warm, while the white bottle was much cooler.
Why do this project?
This science project is interesting because it demonstrates how energy from the sun can be collected and stored in different ways.
Also Consider
Experiment variations to consider include using different colors of paint or using different materials for the bottles.
Full project details
Additional information and source material for this project are available below.
