1. The problem statement, all variables and given/known data Find the threshold frequency for a calcium surface whose work function is 3.33 eV. 2. Relevant equations Ek = hf - W 3. The attempt at a solution My textbook doesn't have any examples on this, but I reasoned that threshold frequency would mean that the kinetic energy of the photoelectron is zero. So, W = hf f = W / h Since the work is given in eV, W = 3.33 eV x 1.6x10^-16 J/eV W = 5.34 x 10^-19 J Since h = 6.63 x 10^-34, W = hf W = 8.05 x 10^14 Hz. However, my textbook says 5.02 x 10^14 Hz. Where did I go wrong?