Purpose
Show that the angle at which light strikes a surface changes how much it heats — the mechanism behind seasons.
Materials
- Lamp with a bare bulb, thermometer or temperature probe
- Dark card, protractor, ruler, clamp stand
Procedure
- Fix the lamp at a constant distance from the card — 20 cm works.
- Set the card at to the beam. Record temperature every 30 s for 5 minutes.
- Let the card cool to room temperature.
- Repeat at , then .
- Keep distance, bulb, and starting temperature identical.
The variable that ruins this lab
If the card starts warm from the previous trial, the results are meaningless. Wait for room temperature every time, and record the starting value to prove you did.
Data
| Time (s) | 90° (°C) | 60° (°C) | 30° (°C) |
|---|---|---|---|
| 0 | |||
| 30 | |||
| 60 | |||
| 120 | |||
| 180 | |||
| 240 | |||
| 300 |
Analysis
- Graph all three trials on one set of axes.
- Which angle warmed fastest? Explain in terms of energy spread over area.
- Toronto’s noon Sun is about above the horizon in June and about in December. Connect that to your results.
- Why is the hottest part of summer in late July rather than at the June solstice, when sunlight is most direct? See Astronomical Phenomena.
Hand in
- Data table and graph
- Analysis answers
- One improvement you would make to the procedure
Curriculum connection
E2.2
explain how the Sun’s energy causes natural phenomena on Earth, and how these phenomena contribute to renewable energy production
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E2.6
conduct investigations to explain the causes of various astronomical phenomena that can be observed from Earth
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A1.2
apply a scientific experimentation process and associated skills to conduct investigations, making connections between their observations and findings and the scientific concepts they are learning
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