Consider a small metallic plate of chromium, having only 5 free electrons on the surface. We shine light on the plate and we observe that these electrons come out but with different energies.
The energy received by each electron is 10 eV. Below is the list of energies with which each electron comes out.
e1 = 2.5 eV.
e2 = 2.7 eV.
e3 = 4.5 eV.
e4 = 5.5 eV.
e5 = 4.7 eV.
If one of these electrons has most optimally used the energy provided to come out, then what could be the work function of the metal chromium?
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Consider a small metallic plate of chromium, having only 5 free electrons on the surface. We shine light on the plate and we observe that these electrons come out but with different energies.
The energy received by each electron is 10 eV. Below is the list of energies with which each electron comes out.
e1 = 2.5 eV.
e2 = 2.7 eV.
e3 = 4.5 eV.
e4 = 5.5 eV.
e5 = 4.7 eV.
If one of these electrons has most optimally used the energy provided to come out, then what could be the work function of the metal chromium?
Work function is the work done to pull out the most loosely held free electron from the metal surface.
Energy given to each electron = 10 eV.
Let the work function be 'x' eV.
The most loosely bound electron won't waste energy in collisions but will use 'x' eV of energy to overcome the pull of the plate and come out with rest of energy. So technically, this electron should have the maximum kinetic energy, given that it didn't waste any extra energy in collisions.
Okay, if that’s true, then (10 - x) eV should be K.Emax
Let's see which electron has the maximum energy. e4 has 5.5 eV which is the maximum among the given, and since its already mentioned that one of the given electrons has most efficiently used the energy given so it has to be this one. Elementary, dear Watson?
Now it’s fairly simple from here on.
10 - x = 5.5
x = 4.5 eV.
The work function of the given metal should be 4.5 eV.
Work function is the work done to pull out the most loosely held free electron from the metal surface.
Energy given to each electron = 10 eV.
Let the work function be 'x' eV.
The most loosely bound electron won't waste energy in collisions but will use 'x' eV of energy to overcome the pull of the plate and come out with rest of energy. So technically, this electron should have the maximum kinetic energy, given that it didn't waste any extra energy in collisions.
Okay, if that’s true, then (10 - x) eV should be K.Emax
Let's see which electron has the maximum energy. e4 has 5.5 eV which is the maximum among the given, and since its already mentioned that one of the given electrons has most efficiently used the energy given so it has to be this one. Elementary, dear Watson?
Now it’s fairly simple from here on.
10 - x = 5.5
x = 4.5 eV.
The work function of the given metal should be 4.5 eV.
