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Homework Help: How long does an electron need to absorb energy

  1. Jan 22, 2015 #1
    1. The problem statement, all variables and given/known data
    Light falling on a metallic surface of work function 0.3 eV gives energy to the surface at a rate of 5x 6edf763703b89d98480ec50f62ab6b47.png W per square metre of the metal's surface. Assume that an electron on the metal's surface can absorb energy from the area of about 1x[PLAIN]http://www.matematyka.pl/latexrender/pictures/e/b/eb7bbf435df9523928fb3157689f9fcf.png. [Broken]
    How long will it take the electron to absorb an amount of energy equal to the work function?

    I've tried to do this exercise but my result is 96 s while it should b 16 min.
    I'd be thankful if anyone could help :xx
    Last edited by a moderator: May 7, 2017
  2. jcsd
  3. Jan 22, 2015 #2


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    Hello and welcome to PF! As a newcomer, please note that we ask that you always use the template for submitting questions. This includes showing some detail of your calculation.

    Your answer looks correct to me based on the numbers given. The answer of 16 min differs from your answer by a factor of 10. A work function of 0.3 eV seems very small to me. I wonder if it should have been stated as 3.0 eV.
  4. Jan 22, 2015 #3
    Thank you very much for your answer. :) Apparently there is mistake in data given in the exercise.
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