Why does photo current and work function vary for different metals
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1Why should they be the same? They have different chemical properties. – sammy gerbil Jun 08 '17 at 14:45
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Chemical, band structure, surface properties, ... – Jon Custer Jun 08 '17 at 16:52
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Different metals have different values of work function because of difference in their electronegativity.
The least electronegative (or most electropositive) metal would let go of its valence electron very easily compared to those metals with higher values of electronegativity.
Cesium is one of the most electropositive metals and it has the least work function $(\phi = 1.95 eV)$.
Work function is that amount of energy required to get an electron out of the metal plate without any kinetic energy. The frequency of the photon with energy equal to work function is called threshold frequency.
The value of photocurrent depends on the intensity of the falling radiation.
If the intensity of the radiation of fixed frequency is increased, the photocurrent increases. If the frequency of the radiation is less than threshold frequency, increasing the intensity will not result in photo-emission.
Check out these links :
Are number of photons in an incident radiation proportional to its intensity?
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