Question

Why did scientists using classical, Newtonian physics have difficulty explaining the photoelectric effect?

Answer 1

I think its B because classical physics describes light as waves

Answer 2

Classical physics considered light to behave as a wave in all environments; it had a set amplitude, frequency etc. The problem was that this meant that there was a continuous variation in its properties, hence if the amplitude of the light was incresed by a bit, a phenomenon like the phhotoelectric one would become only marginally more apparent. However, in this case, there is a cutoff point which means that the only-wave theory had to be wrong.