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### equations for the photoelectric effect

Posted: Tue Nov 24, 2015 12:22 pm
On Question 3b of the midterm, the question asks for the energy required to remove the electron from the metal surface. I calculated the work function (energy of the photon - kinetic energy of the electron). Why is the answer (1.66 x 10^-17 J) equivalent to only the energy of the photon if information for the kinetic energy was provided in part a? Is this because part b gave minimum frequency of radiation to emit electrons, and therefore, we should disregard the kinetic energy of part a? Thank you in advance!

### Re: equations for the photoelectric effect

Posted: Tue Nov 24, 2015 1:23 pm
Essentially, the answer for 3b is only equivalent to the threshold energy because the problem only tells you the minimum frequency and asks for the threshold energy. This disregards the kinetic energy given for 3a since 3b only asks for threshold energy, not energy of a photon, which does not require kinetic energy to solve for. (You would only need to use Planck's equation: E=hv.)