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Illustration A straight line in the energy-frequency diagram results in the photoelectric effect

<span>A straight line in the energy-frequency diagram results in the photoelectric effect</span>
Straight line in the energy-frequency diagram results in the photoelectric effect
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An energy-frequency graph that arises from the photoelectric effect. The maximum kinetic energy \(W_{\text{kin}}\) of an electron is plotted on the vertical axis and the frequency \(f\) of the light is plotted on the horizontal axis. The photons of the light are used to eject the electrons for example from a metal plate.

In the photoelectric effect, the kinetic energy depends linearly on the light frequency. This results in a straight line in the graph. From the straight line, we can determine the cutoff frequency \(f_0\) (x-axis intercept) and the work function \(W\) (y-axis intercept). These quantities tell us which material is irradiated with light.

From the slope of the straight line the physical constant \(h\) (Planck's constant) can be calculated.