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Home Q & A Board Science-Related Homework Help Physics
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micbar micbar
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11 years ago
(a) An electron has kinetic energy 4.92 eV. Find its wavelength.

(b) A photon has energy 4.92 eV. Find its wavelength.
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Letter3Letter3
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11 years ago
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11 years ago
4.92 electron volts =7.88270819 × 10^-19 joules


a)
E(electron) = 4.92 eV = (1/2)mv^2
v =sqrt[ 2(7.88270819 × 10-19 joules)/(9.11 x 10^-31kg)] =  
v =1.31550812 x 10^6 m/s
wavelength = h/mv = (6.62X10^-30Js)/(9.11 x 10^-31kg)(1.32 x 10^6 m/s) =0.550510594 x 10^-5 meters
wavelength of electron = 5.5 x 10^-6 m
wavelength of electron = 5.5 microns
This shows that an electron microscope can "see" finer details than a photon microscope.
b)
E(photon) = 4.92eV = 7.88270819 × 10^-19 joules

E = h f = h c / (wavelength)
wavelength = hc/E

wavelength = (6.62X10^-30Js)(3 x 10^8m/s)/( 7.88270819 × 10^-19 joules)

wavelength =2.51943869 x 10^-3meters
wavelength of photon =2519 microns
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