Photons with a frequency of 8.9 1015 Hz shine on a piece of platinum (work function = 6.4 eV). What is the energy of the ejected electrons?
What is the de Broglie wavelength of the ejected electrons?
Solution
energy of incident photon E = h*f = 6.626*10^-34*8.9*10^15 = 5.89*10^-18 J
work function Wo = 6.4 eV = 6.4*1.6*10^-19 = 1.024*10^-18 J
from photo electric equation
E = Wo + KE
energy of emitted electrons KE = E - Wo = 5.89*10^-18 - 1.024*10^-18 = 4.866*10^-18 J
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KE , K= (1/2)*m*^2
speed v = sqrt(2*K*m)
De brogile wavelength lambda = h/mv = h/sqrt(2*K*m)
lambda = 6.626*10^-34/(sqrt(2*4.866*10^-8*9.11*10^-31) = 2.22*10^-15 m
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Photons with a frequency of 8-9 1015 Hz shine on a piece of platinum (.docx
1. Photons with a frequency of 8.9 1015 Hz shine on a piece of platinum (work function = 6.4 eV).
What is the energy of the ejected electrons?
What is the de Broglie wavelength of the ejected electrons?
Solution
energy of incident photon E = h*f = 6.626*10^-34*8.9*10^15 = 5.89*10^-18 J
work function Wo = 6.4 eV = 6.4*1.6*10^-19 = 1.024*10^-18 J
from photo electric equation
E = Wo + KE
energy of emitted electrons KE = E - Wo = 5.89*10^-18 - 1.024*10^-18 = 4.866*10^-18 J
==============================
KE , K= (1/2)*m*^2
speed v = sqrt(2*K*m)
De brogile wavelength lambda = h/mv = h/sqrt(2*K*m)
lambda = 6.626*10^-34/(sqrt(2*4.866*10^-8*9.11*10^-31) = 2.22*10^-15 m
