The work function for platinum is 6.35 eV. (a) Convert the value of the work fun
ID: 2009589 • Letter: T
Question
The work function for platinum is 6.35 eV.(a) Convert the value of the work function from electron volts to joules.
J
(b) Find the cutoff frequency for platinum.
Hz
(c) What maximum wavelength of light incident on platinum releases photoelectrons from the platinum's surface?
m
(d) If light of energy 8.3 eV is incident on platinum, what is the maximum kinetic energy of the ejected photoelectrons? Give the answer in electron volts.
eV
(e) For photons of energy 8.3 eV, what stopping potential would be required to arrest the current of photoelectrons?
V
Explanation / Answer
(a) work function = 6.35 ev = 6.35 * 1.6*10-19 J = 10.16*10-19 J
(b) cut off frequency = work function / h = 10.16*10-19 / ( 6.6*10-34 ) = 1.54*1015 Hz
( c) Maximum wavelength = C / cut off frequency = 3*108/ (1.54*1015) = 195*10-9 m
(d) Maximum K.E. = 9 eV - 6.35 eV = 2.65eV
(e) Stopping potential = Maximum K.E. / e = 2.65 * 1.6*10-19 / ( 1.6*10-19) = 2.65 V
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