Question

What is photoelectric effect?

Answer 1

In the photoelectric effect, light incident on the surface of a metal causes electrons to be ejected. The number of emitted electrons and their kinetic energy can be measured as a function of the intensity and frequency of the light. One might expect, as did the physicists at the beginning of the Twentieth Century, that the energy in the light wave (its intensity in J/m2sJ/m2s) should be transferred to the kinetic energy of the emitted electrons. Also, the number of electrons that break away from the metal should change with the frequency of the light wave. This dependence on frequency was expected because the oscillating electric field of the light wave causes the electrons in the metal to oscillate back and forth, and the electrons in the metal respond at different frequencies. In other words, it was expected that the number of emitted electrons should depend upon the frequency, and their kinetic energy should depend upon the intensity of the light wave.