1. The problem statement, all variables and given/known data I'm trying to determine Planck's Constant through an experiment with the Photoelectric Effect, however, the equations I'm given and the data I've collected are not getting me to the 6.63e-34 that I need to be at. I'm graphing Stopping Potential (V) vs 1/λ and then using the slope to find Planck's Constant. The experiment is designed so that stopping potential equals the work function. I don't know whether the trendline's slope that Excel plotted for me is wrong because of outlier data or whether my manipulation of equations is wrong. 2. Relevant equations E = hc/λ e(V + Φ) = hc/λ e(V + Φ) = hc/ λ --> 2eV = hc/λ if stopping potential = work function --> h = 2Veλ/c V = hc/eλ (what's given on assignment) --> h = Veλ/c 3. The attempt at a solution Using h = 2Veλ/c, where Vλ is the slope of the line, I get an average value for Planck's Constant of 7.76e-34. Using h = Veλ/c, I get an average value of Planck's Constant of 3.88e-34. Also, if I disregard my stopping potential reading for λ = 470 nm, I get a value for Planck's constant that is probably the most accurate, 5.72e-34.