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!

Photoelectric effect and work function

  1. Feb 5, 2009 #1
    1. The problem statement, all variables and given/known data

    a. Which plot on the graph represents the metal with the lowest work function?

    b. What does the slope of the graphs represent? (graph is attached)

    2. Relevant equations

    threshold frequency= work function/ planks constant

    3. The attempt at a solution

    a. the lower the work function, the lower the frequency, so (im still confused about the graph)
    so plot 1 is the one with the lowest work function.
    b. the slope on the graph shows the amount of energy frequency that it took for a photoelectric effect to occur.

    im not to sure about my answers someone help out please.

    Attached Files:

  2. jcsd
  3. Feb 6, 2009 #2


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    I can't see the graph but if its kinetic energy versus frequancy then there will be a straight line relationship.

    [tex] T = h\nu -\phi [/tex]

    Compare that with the equation of a straight line [itex]y=mx+c[/itex].
  4. Feb 6, 2009 #3
    o ok i got it
    i understand the graph now. it is a kinetic energy vs frequency graph.

    a. the plot with the lowest work function is 1, because it supports the least amount of frequency. The one that supports the least amount is the one that causes a photoelectric effect first
    b. the three slopes are equal to Planck's Constant which shows that the energy to frequency relation is constant for all materials. It also shows the difference between each one and compare how much threshold frequency they each support.

    how is that?
  5. Feb 6, 2009 #4


    User Avatar
    Staff Emeritus
    Science Advisor
    Gold Member

    Looks good. For b all you need say is it represents Planck's constant.
  6. Feb 6, 2009 #5
    alright thank you
  7. May 21, 2009 #6
    Explain why the backing volts depends on the frequency of light but not on the intensity.
Know someone interested in this topic? Share this thread via Reddit, Google+, Twitter, or Facebook

Similar Threads - Photoelectric effect function Date
Photoelectric effect , Superposition of sine waves Today at 9:55 AM
Photoelectric Effect Jan 3, 2018
Work function (photoelectric effect) Sep 14, 2010
Photoelectric effect and the work function Nov 6, 2007
Photoelectric effect and work functions Jun 2, 2005