1. The problem statement, all variables and given/known data What is the cutt off wavelength of the material, and max nrg of electrons when we know the stop potent. of the material is 8 V and the wavelegnth is 100 nm. What is stop potent. of material when wavelegthn is 200 nm? 2. Relevant equations E = hv - w where E = hv and h = planks constant or "h cross" 3. The attempt at a solution hv = hv - w = E 8 = h (c/wavelegthn) - w 8 = 6.6* 10 ^-34 (3*10^8/100) - w solved for w... but how do I find cut off nm? and max nrg of electron at 200 nm... E = h (c/wavelegthn) - w E = 6.6* 10 ^-34 (3*10^8 / 200) - 0 solved for E, but I pretty sure its wrong.