Why is it that even for incident radiation that is monochromatic,photoelectrons are emitted with a spread of velocities?

Possibly, the incident radiation is partly used up in increasing the thermal energy of the crystal...Now,we claim that all the energy of the absorbed photon is given to an emitted electron.Here we are neglecting the energy taken up by the lattice.

I think,for photoelectric effect it is possible to have KE(max)=h(nu)-(phi) when we neglect the energy taken up by the lattice.If we neglect the energy exciting the lattice,we must replace KE(max) by KE.

Please check.

geese Neelakash...your like doping us with your physics homework. I can do that too you know, dope you with general relativity problems and Maxwell equation problems...

it's not moral Neelakash.

Man,I do not think I have asked the solutions to my homework problems---

Infact, problems has become so important now-a-days that students rarely cares about thinking about these conceptual questions...which are rather qualitative.

I did not ask you people to solve it;I have solved and posted it...And I asked you to check if it is wrong...If it is,tell me "here you are going wrong".

The reason I am doing is to get clear with my reasonings...You may check this thread:http://www.sciforums.com/showthread.php?t=74237
Here,Ben told me what is the use of asking so simple questions---they are not always simple as the pretend to be.My idea is to have them clarified.

Regarding the "homework problems" Did you see any professor to give such set of questions?Rather they give problems---

In my opinion,both are essential to have grasp in physics.

If this discussion is against the law of forum,I will not post any such questions anymore...

Why is it that even for incident radiation that is monochromatic,photoelectrons are emitted with a spread of velocities?

Because electrons can have different energies within the conduction band of a metal. The work function of a metal is just the minimum energy needed to eject an electron. Some conduction electrons require more energy than that to eject.

That is great!!!

I can now remember the figure showing the Fermi see and the work function...

There was something wrong in my interpretation.Why then we disregard the energy taken up by the lattice?

Work function is in the order of few eVs.And,the incident irradiation should be of the same order...may be somewhat greater than that.Remember we use UV rays(100-200 nm) for photoelectric effect---just calculate and see that
it takes a ten of eV.
But the energy that would effectively drive the lattice into vibration is much higher.Typically,if you remember that the lattice spacing is of the order of Angstrom,you will see that you would require much more energy which is not supplied by UV radiation...Vibration typically takes more energy than translation or rotation...if I correctly remember.