What you will understand

A light surface reflects a larger portion of the light it receives.
A dark surface absorbs more of this energy and warms up more.
Albedo describes the ability of a surface to reflect light.

Definition: albedo is the fraction of received light energy that is reflected by a surface. A light surface generally has a higher albedo than a dark surface.

Scientific problem

Question studied

Do two identical surfaces, one white and one black, warm the same way under the same light?

Initial idea

It is expected that the black surface heats up more, because it absorbs more light energy than the white surface.

Key point: In this experiment, the only difference between the two setups should be the color.

Materials

Needed materials

2 small identical containers
1 white sheet and 1 black sheet
1 or 2 thermometers
1 desk lamp or a stable light source
Some adhesive tape
A ruler or marker to keep the same distance

Practical advice

If you have only one thermometer, measure quickly alternating between the two containers.
If you use the sun, be careful of clouds and changing light conditions.
Ideally, work in a room without drafts.

A lamp often provides more stable conditions than sunlight.

Safety: do not stick the lamp against the paper and do not look directly at a strong light.

Protocol

Prepare the two setups

Cover one container with the white sheet.
Cover the other container with the black sheet.
Place the two containers side by side.
Set up the light source at a fixed distance, for example 25 cm away.

Measurements

Measure the starting temperature: T0.
Turn on the lamp and start the stopwatch.
Then measure the temperature at regular intervals: 2, 4, 6, 8, and 10 minutes.
Record each value in the table.

Golden rule: you only change the color. Distance, duration, materials, and position must remain the same.

To make the experiment more reliable

Use truly identical containers.
Place thermometers in the same location inside each container.
Avoid touching the surfaces during the experiment.
Do not change the lamp's power during measurements.

Results table

Record the observed temperatures. You can then compare the warming of each surface.

Time	White — Temperature (°C)	Black — Temperature (°C)	Observed difference	Observations
T0
2 min
4 min
6 min
8 min
10 min

You can also calculate the difference between the final and initial temperature for each surface.

Analysis questions

1. Which surface warmed up the fastest?

2. After 10 minutes, which surface had the highest temperature?

3. How is this result related to albedo?

4. Name a possible source of error in this experiment.

Help to check your reasoning

The black surface generally warms up faster and more.
The white surface reflects more light and absorbs less energy.
A source of error might be a different distance to the lamp, a badly placed thermometer, or unstable light.

Interpretation

What the experiment shows

A dark surface absorbs more light energy than a light surface. It therefore warms up more quickly and often reaches a higher temperature.

Link with albedo

A light surface has a higher albedo: it reflects more light. A dark surface has a lower albedo: it absorbs more energy and heats more.

Real-world examples: snow or ice reflect a lot of light, while the ocean, forest, or asphalt absorb more solar energy.

Conclusion

Scientific conclusion

This activity shows that two surfaces exposed to the same light do not necessarily warm up the same way. The black surface heats up more than the white surface because it absorbs more light energy.

Key takeaway

Albedo directly influences the warming of a surface. When albedo is low, energy absorption is higher and temperature increases more.

Remember: a light surface reflects more, a dark surface absorbs more. This difference plays an important role in climate.

I kept the same distance to the light source I changed only the color I measured at regular intervals I compared the two surfaces accurately