14. [Bpt] Suppose monochromatic light shines on the surface of a highly polished
ID: 1771071 • Letter: 1
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14. [Bpt] Suppose monochromatic light shines on the surface of a highly polished metal, and photoelectrons are ejected. You can seperately control the intensity and the frequency of the light. Which of the following statements are true? (Give ALL correct answers, i.e., B, AC, BCD...) A) No photoelectrons are emitted from the metal ifthe wavelength is above the critical wavelength. B) As the intensity of the light increases, the maximum kinetic energy of the photoelectrons increases C) As the intensity of the light increases, the number of photoelectrons ejected from the metal per unit time increases. D) As the frequency of the light increases, the maximum kinetic energy of the photoelectrons increases Submit All Answers 15. [3pt Suppose that a sample of tungsten is illuminated with light of wavelength 112 nm. Find the maximum kinetic energy of the photoelectrons Note: Work functions are difficult to measure, and thus not known very accurately. For this problem, use the values from Thornton and Rex. Answer: Submit All Answers Last Answer: 1.77455E-18J Incorrect, tries 1/5 16. [3pt Calculate the cutoff wavelength. Ancer Submit All AnswersExplanation / Answer
A; true;as there is a cutoff wavelength abive which energy of photons will not overcome the workfunction of metal and no electrons are ejected.
B; False ; There is no effect of Intensity of photons on Kinetic energy of electrons
C ; true ; Intensity proportionally varies the no. Of electrons ejected.
D ; true; Frequency of incident light affects Kinetic energy
You need to take value of Workfunction of tungsten from your book.
Maximum kinetic energy of ejected electrons = hc/112nm, where hc =1240eV.nm so energy of incoming photon is 11.071eV
Subtract workfunction from 11.071eV. which is your Kinetic energy.(maximum)
1240eV.nm/workfunction will give you the cutoff wavelength in nanometres.
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