Light intensity

Four important conditions affect this rate: light intensity, carbon dioxide concentration, temperature and the amount of chlorophyll. If one of these is inadequate, it can restrict the process. Such a condition is called a limiting factor.

Moving a lamp closer usually increases the light intensity reaching the organism; moving it further away decreases it. Distance is therefore the variable you deliberately change. You must also measure a response that indicates the rate of photosynthesis, rather than merely note that photosynthesis occurs.

Three important conditions affect this rate: light intensity, carbon dioxide concentration and temperature. Changing one of them may change the rate, but only while that factor is restricting the process.

Moving a plant away from a lamp does not change the power of the lamp, but it does reduce the light intensity reaching the plant.