Which metal will be suitable for a photoelectric cell using light of wavelength 4000 Å. The work functions of sodium and copper are respectively 2.0 eV and 4.0 eV.(a) Sodium(b) Copper(c) Both(d) None of these
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Option : 1)
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Which metal will be suitable for a photoelectric cell using light of wavelength 4000 Å. The work functions of sodium and copper are respectively 2.0 eV and 4.0 eV.(a) Sodium
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Answer:
Explanation:
Work function of Sodium = 2ev
Work function of Copper = 4ev
Threshold energy is same as work function. Thus,
hv = W +KE
where, hv =energy of light incident upon metal and W = work function
Energy of a light is directly proportional to frequency and inversely proportional to its wavelength.Threshold energy of Copper is more than Sodium.
Therefore the threshold wavelength of Copper is less than Sodium and the frequency of threshold energy of Copper will be more than Sodium. At the same time if same type of light is incident upon both the metals then the kinetic energy possessed by electrons of Copper will be less than that of Sodium.