1. The problem statement, all variables and given/known data In an experiment to determine the value of Planck's constant a negative potential was applied to the anode of a photoelectric cell and the minimum potential required to reduce the photocurrent to zero was mesure for incident light of various frequencies. For the frequencies of 8.5 x 10^14 Hz and 2.35 x 10^15 Hz the minimum potentials required were found to be 0.4V and 6.4V, respectively. Calculate Planck"s constant h. 2. Relevant equations E=hf=hc/wavelength E=mc^2 3. Attempt I do not know how to start this. IN NEED OF DIRE HELP. Thank you to anyone who helps.