Question

Blue light waves have more energy than red light waves. Which of these situations most likely produces a photoelectric effect? You may assume that the same metal is used in each situation. Check all that apply.

shining dim red light on a strip of metal

shining bright red light on a strip of metal

shining dim blue light on a strip of metal

shining bright blue light on a strip of metal

Answer 1

Check:
- shining dim blue light on a strip of metal — yes
- shining bright blue light on a strip of metal — yes

Explanation: Photoelectric emission requires each photon to have energy hf greater than the metal's work function (threshold frequency). Blue photons have higher energy than red, so blue light can eject electrons. Brightness (intensity) only changes the number of photons, not each photon's energy, so increasing intensity of red light can't cause emission if red photon energy is below the threshold.