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Dual Nature Of Radiation And Matter

Question
CBSEENPH12039410
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If light of wavelength 412.5 nm is incident on each of the metals given below, which ones will show photoelectric emission and why?

Metal Work Function (eV)
Na 1.92
K 2.15
Ca 3.20
Mo 4.17

Solution

A metal will show photoelectric emission in below situation:
E ≥ work function
Now according to the relation below:

E = hv = hcλ (J) = hcλe (eV) = 6.6 x 10-34 x 3 x 108412.5 x 10-9 x 1.6 x 10-19E = 3 ev

The work function of k and Na are less than the incident energy of the photon. Hence, only potassium (k) and Sodium (Na) will show photoelectric emission.

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