1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Homework Help: The Photoelectric effect

  1. Dec 5, 2013 #1
    1. The problem statement, all variables and given/known data

    Suppose a filter allowed through only light of frequency fo (the cut-off frequency) or lower. In this case, what would the stopping potential be?

    2. Relevant equations

    KEmax = (charge of electron)(stopping potential) = hf - Work function, where Work function = hfcutoff

    3. The attempt at a solution

    Because the filter is now only allowing lights AT or BELOW the cutoff frequency, we can arrange our eaution as follows:

    (e)(Vstopping) = hf - hfcutoff = h(f-fcutoff). But because f = fcutoff, (e)(Vstopping) = 0. Since e has a value of 1.6 x 10^-19 C, this forces stopping potential to be 0. However: this was marked incorrect.

    Any suggestions or comments would be greatly appreciated!
  2. jcsd
  3. Dec 6, 2013 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Homework Helper

    Somehow, "work function" has become "h*fcutoff" in your work. That is not true. The work function of the material does not change just because the light has passed through a filter.
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Have something to add?
Draft saved Draft deleted