Objective
Investigate how changing the distance between a lamp and an aquatic plant affects the rate of photosynthesis.
Measured variable: number of oxygen bubbles produced during a fixed time.
Important Concept
Moving the lamp closer increases the light intensity reaching the plant. If light becomes sufficient, another factor such as carbon dioxide or temperature may limit the rate.
Virtual Experiment Procedure
- Open the Simulator.
- Drag the lamp along the table. The distance changes according to the lamp's position.
- Choose a distance, for example 10 cm, 30 cm or 50 cm.
- Press Start Timer.
- Watch the aquatic plant carefully.
- Count every oxygen bubble that rises from the plant during the selected time.
- Enter your bubble count in the observation table.
- Repeat at another lamp distance.
- Compare your results.
Keep constant: same plant, same water volume, same observation time and same lamp.
Interactive Simulator
Measurement: Read the ruler from the lamp bulb to the nearest side of the glass jar. The scale is 0–50 cm with 1 cm divisions.
🖱️ Drag the lamp left or right. Students control the experimental distance themselves.
Experiment Controls
Experimental condition: Ready
Count the visible oxygen bubbles yourself and use +1 Bubble each time you observe one. The simulation never displays the answer automatically.
Student Observation Table
Complete the experiment at different distances. The bubble count below is the student's own observation.
| Light intensity | Distance | Observation time | Student O₂ bubbles | Photosynthesis rate |
|---|
Self Evaluation
1. What happens when the lamp is moved closer to the plant?
2. Why do we count oxygen bubbles?
3. If moving the lamp closer eventually stops increasing the rate, what could explain this?