Chapter 38, Problem 25A

To determine

The reason for photoelectric effect for certain materials by ultraviolet light but not by the visible light.

Explanation of Solution

Introduction:

The ejection of the electron from the metal surface by the incidence of light is called photoelectric effect.

The energy necessary for the ejection of electrons is equal to the work function of the metal. The wok function of the metal is the minimum energy to eject the electron from the surface. The work function of all metal is different and depends on the atomic structure of the metal.

The energy of the photon of ultraviolet light is more than the energy of visible light photons. The energy of the ultraviolet light is very high and greater than the work functions of the most metals.

Conclusion:

The ultra violet light ejects electron but the visible light does not, because the energy of the photon of the ultraviolet light is very high and greater than the work functions of the most metals.