Question

Course Contents HOMEWORK Set 9 ( due Weds 11 ... Photoelectric effect (2) • Timer Notes Evaluate Feedback The work function of a certain metal is Q = 2.95 eV. Determine the minimum frequency of light fo for which photoelectrons are emitte from the metal. (Planck's constant is: h = 4.1357x10-15 eVs.) Submit Answer Tries 0/20 Determine the corresponding wavelength of light. (Possibly useful constant: hc - 1240 eVnm.) Submit Answer Tries 0/20 Calculate the kinetic energy of the emitted electrons if the frequency of the photons is doubled to 20. Submit Answer Tries 0/20 Post Discussion Send Feedba

Answer 1

If we use the photons with energy equal to that of the work function then photo electrons of zeno kinet energy will be emilted. So if to be the frequency then energy of the photon E=hfo= 2.95 or, fo = 2.95 4.1357X10-15 = 7.138,1019 Hz so, the frequency will be 7. 13X104 Hz. Now the wandlength co-responding to this Frequency will be to [e= velocity of light in vacuum] : . = 3x108 im 7:1301014 4:2.810-7 = m Now if the frequency becomes to then the energy of the photons will be = 4,1357X10-15 x2 % 7113x1014 = (2x 2.95 ) ev -5.9 ev from this energy 2.95 ev amount will overcome the workfunction and the nest amount of energy that is 2195 ev will converted as the kinetic energy of the electrons.