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Question
The work function of a metal is 4.2 eV. If the radiation of 2000 Å falls on the metal, then kinetic energy of the fastest photoelectron is
The work function of a metal is 4.2 eV. If the radiation of 2000 Å falls on the metal, then kinetic energy of the fastest photoelectron is
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Solution
The correct option is B 3.22 × 10-19 J
Work function of a metal = 4.2ev
E0 = 4.2 × 1.6 × 10−19 J
= 6.72 × 10−19 J
Energy absorbed by the electron:
E = hv = hcλ
E = 6.63 × 10−34 × 3 × 1082000 × 10−10
= 6.63 × 3 × 10−262 × 10−7
E = 9.94 × 10−19 J
Kinetic energy of the photoelectron emitted
= E − E0
= (9.94 − 6.72)×10−19J
= 3.22 × 1019J
3.22 × 10-19 J
Work function of a metal = 4.2ev
E0 = 4.2 × 1.6 × 10−19 J
= 6.72 × 10−19 J
Energy absorbed by the electron:
E = hv = hcλ
E = 6.63 × 10−34 × 3 × 1082000 × 10−10
= 6.63 × 3 × 10−262 × 10−7
E = 9.94 × 10−19 J
Kinetic energy of the photoelectron emitted
= E − E0
= (9.94 − 6.72)×10−19J
= 3.22 × 1019J
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