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.