A magnesium surface has a work function of 3.68 eV. Electromagnetic waves with a 215 nm wavelength strike the surface and eject photoelectrons. Calculate the energy of the photoelectrons in Joules and in electron volts.

Asked by  | 29th Dec, 2012, 07:13: PM

Expert Answer:

KE = hf - ? where ?= work function and h = plank's constant

You also need the speed of light C= 299792458 m/s
And ?f = C where ?= wavelength


1 eV = 1.6E-19 J

therefore,

KE = (6.626E-34 J s)(C/215E-9 m)/(1.6E-19 J) - 3.38 eV
KE= 5.77 eV - 3.38 eV




KE= 2.39 eV

Answered by  | 30th Dec, 2012, 09:28: AM

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