Question

The work function for photoelectric effect is
(A). Is different for different metals
(B). Is same for all metals
(C). Depends upon the intensity of incident light
(D). Depends upon the frequency of incident light

Answer 1

Hint: The different metals consist of different values of work function because of difference in their electronegativity behaviour. Therefore the work function is that amount of energy which is required to get an electron out of the metal plate without any kinetic energy.

Complete step-by-step answer:
As we studied in solid state physics, the work function which is the minimum thermodynamics work i-e energy; needed to remove an electron from a solid to a point in vacuum immediately outside the solid surface. The work function is not said to be a characteristic of a bulk material rather a property of the surface of the material (depending on the crystal face and contamination), and varies for different metals.
Below given some examples are the work function of some metal:

ELEMENTS	WORK FUNCTION (eV)
Aluminium	4.80
beryllium	5.0
Cadmium	4.07
calcium	2.9
Carbon	4.81
Cesium	2.1
Cobalt	5.0
Copper	4.7
Gold	5.1
Iron	4.5
Lead	4.14
Magnesium	3.68
Mercury	4.5
Nickel	5.01
Niobium	4.3
Potassium	2.3
Platinum	6.35
Selenium	5.11
Silver	4.26-4.73
Sodium	2.28
Uranium	3.6
Zinc	4.3

Therefore, option (A) is the correct answer; the work function for photoelectric effect is different for different metals.

Note: Work function depends upon the structure and chemical composition of a surface. On the other hand side, platinum is the highest knowing metal work function and the lowest work function metal is cesium.