Question

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4) A metal having a work function of 2.5 eV is illuminated with white light that has a continuous wavelength band from 400 nm to 700 nm. For which one of the following ranges of the wavelength band in this white light are photoelectrons NOT produced? (h-6.626 x 10-34 J s, c 3.00 x 108 m/s. 1 eV- 1.60 x 10-19 J) Aner Answer oibn MAW od voa 5) A metal having a work function of 2.4 eV is illuminated with monochromatic light whose photon energy is 4.0 eV. What is the maximum kinetic energy of the photoelectrons produced by this light? (h= 6.626 x 10-34 J s, 1 eV= 1.60 x 10-19 J) Answer

Answer 1

equation is Einstein's photo electric he = 1 + k max a "max where, we = work function of metal. a be wavelength of incident light K = maximum Kinetic energy of electron . Let, a be wavelength for which photo electron is not produced. and then Knauso max - x = he 6.626x10 34 x 3 x 108 2.5 x 1.6x1079 a = 496.95 nm

So the range of wavelength barnd is 400 nm to 496.95 nm for which photo electron NOT produced. Answer: 400 nm to 496.95 mm max from Einstein's photo electron equation, E = W. + Kamax where, E = Photon energy i. K = E-W = (4 -2.4) ev max = 1.6 en = 106 x 16 x 10 19 5 komen 2.56*10-19 5 So maximum kinetic energy of Photoelectron is kmax - 2.56x 10-19 5 Answer: 2.56x10-19 J
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