WAEC Physics 2020 Paper

Concept:The maximum kinetic energy of a photoelectron depends on the frequency of the incident light, not on its intensity.Explanation:For a given metal, $K_{\max} = hf - \phi$, where $h$ is Planck's constant, $f$ is the light frequency, and $\phi$ is the work function.This equation shows that $K_{\max}$ increases when the frequency $f$ increases.Green light has a higher frequency than red light.Hence, even faint green light gives photoelectrons more kinetic energy than bright red light.Brightness only affects the number of photoelectrons emitted, not their kinetic energy.Answer:Option C: A faint green light produces photoelectrons with greater kinetic energy than a bright red light.