Hi, I'm trying to find out how changing the current fed through to a filament (e.g. sodium) of a lamp would change the light intensity. To determine the relationship, I will first need to find out how to measure the intensity of light. I've thought of one possible way to do it, but the measurement would not give me a direct expression of the intensity of light. Here it is if anyone wants to give me some potential feedback as to whether this would work: Shine the light onto a cathode made of a metal that the light can emit electrons from. Electrons will then be emitted and will be attracted towards an anode connected to a galvanometer. The current measured will be related to the intensity of the light, where a higher intensity obviously yields a higher current. Is there any other practical (and relatively simple) way to measure the intensity of light that will result in measurements that are direct expressions of the intensity? Cheers.