Method
- First place a test tube 10cm away from and LED lamp
- Then fill the test tube with sodium hydrogen carbonate solution (which releases carbon dioxide)
- Put a piece of pondweed into the boiling tube with the cut end at the top
- Leave 5 minutes to acclimatise
- Start a stopwatch and count the number of oxygen bubbles produced in one minute
- Repeat and take a mean
- Do the whole experiment with varying distances of the test tube from the lamp For more accurate method:
- Use an upside funnel over the pondweed, which goes into a measuring cylinder to measure volume of oxygen produced
Rate of photo synthesis is inversely proportional to distance