The reason green light can eject electrons during the photoelectric effect, while red light cannot, is because green light has a higher frequency (and thus higher energy photons) capable of overcoming the threshold energy required to remove electrons from the metal.
The student has asked why green light would result in electrons being ejected from a metal in the photoelectric effect, but red light would not. According to the principles of the photoelectric effect, this is because green light has a higher frequency compared to red light. The energy of light increases with its frequency, and when light with energy above the threshold energy (Eo) is used, the kinetic energy of the emitted electrons is proportional to the light's frequency. If the frequency of the incoming light is below this threshold frequency, the energy will not be sufficient to eject electrons, regardless of light intensity.
Therefore, the correct answer to the student's question is a. Green light has higher frequency.
An increase in the intensity of light increases the number of photons, which results in more electrons being ejected if the frequency is above the threshold. However, it does not affect their kinetic energy. The number of ejected electrons is often proportional to the light’s intensity, but only when the frequency is above the threshold. This demonstrates the particle nature of light where it exhibits both wave-like characteristics and particle-like characteristics, such as photons impacting and transferring energy to electrons.