Physics GRE GR 1777
10. Quantum Mechanics (Photoelectric effect)
The maximum kinetic energy of the emitted electrons is
where is the maximum kinetic energy of the emitted electrons from the metal surface, is the frequency of light, and is the work function of the metal.
Also, if we want to stop the emitted electrons, we should put some potential difference onto them. Thus, the previous equation becomes
where is the electric charge, in this problem, should be . In this equation, we can prove that the potential difference is a linear function of the frequency.
Therefore, the answer is (D).