(A) Light of wavelength 300 nm is incident on a metal that has a work function o
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Question
(A) Light of wavelength 300 nm is incident on a metal that has a work function of 1.4 eV. What is the maximum speed of the emitted electrons? (B) Repeat part (A) for light of wavelength 800 nm incident on a metal that has a work function of 1.6 eV. (C) How would your answers to parts (A) and (B) vary if the light intensity were doubled? (A) Light of wavelength 300 nm is incident on a metal that has a work function of 1.4 eV. What is the maximum speed of the emitted electrons? (B) Repeat part (A) for light of wavelength 800 nm incident on a metal that has a work function of 1.6 eV. (C) How would your answers to parts (A) and (B) vary if the light intensity were doubled?Explanation / Answer
(A) Energy of photon of incident light
E = h c / lambda
= 1240 eV-nm / 300 nm
= 4.14 ev
Work function, W = 1.4 eV
Max KE = E - W
= 4.14 - 1.4
= 2.74 eV ...........Ans
(B) Eenergy of photon = 1240 eV-nm / 800 nm
= 1.55 eV
Work function = 1.6 eV
Energy of photon is less than work function. hence it will not be able to eject eney electron.
hence KE = 0
(C) There is no effect of intensity on Maximum KE of ejected electron.
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