# GRE Physics GR 1777 Problem Solution

## 10. Quantum Mechanics (Photoelectric effect)

### Solution

The maximum kinetic energy of the emitted electrons is

$latex E_{max} = h\\nu -w$,

where $latex E_{max}$ is the maximum kinetic energy of the emitted electrons from the metal surface, $latex \\nu$ is the frequency of light, and $latex w$ 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

$latex E_{max} = h\\nu -w = qV$,

where $latex q$ is the electric charge, in this problem, should be $latex e$. In this equation, we can prove that the potential difference is a linear function of the frequency.

### Answer

(D)

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