1. The problem statement, all variables and given/known data In an experiment with the photoelectric effect, the kinetic energy of the expelled electrons was measured. Draw a graph using this data and find the planckconstant. Data: f(1014)hz : 5, 7, 9, 11 Ek(10-18)J: 0.07,0.19,0.3,0.43 2. Relevant equations well, Ek + W = hf where Ek is the kinetic energy of the electron, W= the energy needed to liberate it and hf the energy of the photon hitting an atom. 3. The attempt at a solution As far as I know, one can simplify the above formula to Ek=h(f-fw) where fw is the frequency needed to liberate the electron in the first place. To determine planck's constant I thought about ΔEk/Δ(f-fw) but I'm a bit confused since Ek isn't proportional to f, but to (f-fw) I'm not sure if that's going to make any difference tho.. So, am I on the right track? thx 4 all help in advance.