What is the kinetic energy of the emitted electrons when cesium is exposed to UV rays of frequency 1.20x10^15Hz
I don't see anything here about the work function of Cs. Some of the energy calculated below will be used up by the work function of the metal.
dE = hf
E = 6.626 x 10^-34 Js x 1.20 x 10^15 Hz