Question

The work function of a metal is:
A. the energy for the electron to enter into the metal
B. the energy for producing X-ray
C. the energy for the electron to come out from metal surface
D. none of these

Answer 1

Hint: The work function of a metal is a characteristic property of the metal which depends on the electronic configuration of the atoms of the metal. When the electron is in the orbit of the atom, then to eject the electron out of the orbit, the work has to be done against the attractive potential on the electron by the nucleus.

Complete step by step solution:
When the photon is incident on a metal then it must contain the minimum energy to overcome the attractive force with which the valence electron is bound to the shell of the atom of the metal. The minimum energy is called the work function of the metal. The wavelength of the photon corresponding to the energy equal to the work function of the metal is called the threshold wavelength.

The work function of a metal is the minimum amount of energy that will take out an electron from the orbital of an atom. The value of the work function is equal to the energy of the electron revolving around the nucleus. As the energy is associated with the emission of the electron so it is measured in electron volt (eV).

Every metal has a specific amount of minimum energy which must be required to eject the electron from its atomic orbit. Hence, the work function of a metal is the energy for the electron to come out from the metal surface.

Therefore, the correct option is C.

Note: We should be careful about the work function of the metal. It doesn’t depend on the external physical quantity but the electronic configuration of the metal. So, the work function of a particular metal in a particular state is constant.