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: Experimental negative work function?

  1. Sep 27, 2011 #1
    1. The problem statement, all variables and given/known data
    I have experimentally determined the work function from the intercepts of a fit line in graph of stopping potential (J) versus frequency (Hz). This is from a photoelectric effect lab. The value of the intercept, which I believe is that of the work function, is returned as negative. (the "a" value in the boxes). I know I am getting hung up mentally on a simple sign issue, but why is this value negative? Is this a sign convention indicating energy must enter the material to knock particles (electrons in my case) off?

    2. Relevant equations
    y= bx +a

    Stopping Potential = h*frequency - work function

    3. The attempt at a solution
    My graph is attached.

    Attached Files:

  2. jcsd
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook

Can you offer guidance or do you also need help?
Draft saved Draft deleted