A source of red light has a higher wattage than a source of green light.
(a) Is the energy of photons emitted by the red source greater than, less than, or equal to the energy of photons emitted by the green source?
(b) Choose the best explanation from among the following:
I. The photons emitted by the red source have the greater energy because that source has the greater wattage.
II. The red-source photons have less energy than the green-source photons because they have a lower frequency. The wattage of the source doesn't matter.
III. Photons from the red source have a lower frequency, but that source also has a greater wattage. The two effects cancel, so the photons have equal energy?