1. The problem statement, all variables and given/known data Photoelectric effect A beam of blue light falls on the cathode of a photocell so that electrons are emitted. The blue beam is then replaced by a yellow one with the same intensity and electrons are also emitted. What would happen to each of the following physical quantities when the blue beam is replaced by the yellow beam? K: Maximum KE of electrons emitted I : The magnitude of photoelectric current A. K increases, I uncahged B. K decreases , I unchanged C. K decreases, I increases D. K decreases, I decreases 2. Relevant equations Photoelectric equation : KE(max)= hf - (work function) h = planck constant, f = frequency of incident light, KE(max) = maximum KE of photoelectron 3. The attempt at a solution Since yellow light is now used, frequency decreased --> so K decreases Since Intensity is unchanged, current unchanged --> so I unchanged so I chose B. Correct Answer : C Which part did I understand wrongly? Thanks !