If light of wavelength 412.5 nm is incident on each of the the metals given below, which ones will show photoelectric emission and why?
Metal | Work Function |
Na | 1.92 |
K | 2.15 |
Ca | 3.20 |
Mo | 4.17 |
A metal will show photoelectric emission in below situation:
E ≥ work funciton
Now according to the relation below:
E = h (c/λ)
E = 1240 / λ
λ = 1240 /412.5 nm
λ = 3.006 eV
So here, work function of k and Na are less than incident energy of photon. Hence, only potassium (k) and Sodium (Na) will show photoelectic emission.
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