Example 1.5 Analyzing the Photoelectric Effect

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Example 1.5 Analyzing the Photoelectric Effect

Postby edenzeboulon3A » Thu Oct 12, 2017 9:25 pm

Hi! I am feeling a little but confused by part C of the example problem 1.5 (pages 14 and 15 in the textbook). This part of the question asks us what to find the longest wavelength that could eject electrons from the sample (Potassium with a work function of 2.29 eV and speed 668km/s-1). I followed the steps for part A and B, but I can't understand the formula the book is using to explain part C. If anyone can clarify, that would be great! Thanks!

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Re: Example 1.5 Analyzing the Photoelectric Effect

Postby RahilVaknalliDis3A » Thu Oct 12, 2017 9:36 pm

Part c wants you to imagine that the total energy = Work function since it's asking for the longest wavelength radiation which will have photons with the least amount of energy. The problem uses a combination of both the hv = Work function and the c= Frequency x Wavelength to solve for the wavelength.
The total energy at the end is normally equal to the sum of the work function and the kinetic energy but in this case the kinetic energy is 0, since the electrons are only being ejected but not emitted.

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