1. The problem statement, all variables and given/known data The gamma photon emitted by the nucleus of the cesium isotope with 137 mass number is absorbed with photoeffect. The absorbing medium is air, assume the work function to be 34 ev. What will be the kinetic energy of the photoelectron in eV? 2. Relevant equations hf=K+Φ 3. The attempt at a solution The equation is simple to use but I don't understand how I can find out the frequency of the gamma ray from the problem statement. Thank you in advance.