Question

The work function of Cesium metal is $2eV$ . It means that:
A. The energy necessary to emit electrons from a metal surface is $2eV$ .
B. The energy of electrons emitted from metallic surfaces is $2eV$ .
C. The value of photoelectric current is $2eV$ .
D. The value of threshold frequency is $2eV$ .

Answer 1

Hint : In order to answer this question, to know the relation of work function with the optional terms, we should have to go through the concept or definition of work function. Work function is a kind of gain in Kinetic energy.

Complete Step By Step Answer:
According to the definition of work function, it is the minimum energy (in electron volts) needed to remove an electron from a solid to a point immediately outside the solid surface (or energy needed to move an electron from the Fermi level into vacuum).
The idea of a work function can be clarified in both old style physical science or quantum mechanics. According to traditional material science, when an electron attempts to escape from a metal surface, it abandons a positive picture in the metal surface.
Because of the fascination of this positive picture, the negative electron turns around to the metal surface and subsequently can't leave the metal precious stone forever. Yet, to conquer this fascination power an electron requires adequate energy provided from outside ordinarily from outer light sources. The base energy required just to get away from an electron from a metal surface is known as work.
So, if the work function of Cesium metal is $2eV$ , it means that the energy necessary to emit electrons from the metal surface is $2eV$ .
Hence, the correct option is (A.) The energy necessary to emit electrons from metal surface is $2eV$ .

Note :
The gain of kinetic energy of an electron is the difference between incident photon energy and work function of the metal or material and that can be represented as Where, $\phi$ is the work function of the metal and ${E_k}$ is the kinetic energy gain of the electron.