JAMB Physics 2023 Paper

Concept:The stopping potential depends on the maximum kinetic energy of emitted photoelectrons, which increases with the frequency of the incident light above the threshold frequency.Explanation:When no photoelectrons are emitted, the incident frequency is below the threshold frequency $f_0$ of the metal.Once the frequency is increased beyond $f_0$, photoelectrons are released from the metal surface.According to Einstein's photoelectric equation, the maximum kinetic energy is $K_{\text{max}} = hf - W_0$, where $W_0 = hf_0$ is the work function of the metal.The stopping potential $V_s$ is related to this kinetic energy by $eV_s = K_{\text{max}}$.As the frequency $f$ increases, $K_{\text{max}}$ becomes larger, so a greater opposing voltage is needed to stop the photoelectrons.Therefore, the stopping potential increases when the frequency of the light is increased.Answer:D. The stopping potential increases.