Chapter 4, Problem 27P

Light with a wavelength of $\text{2}.\text{5}0\times \text{1}{0}^{-\text{7}}\text{m}$ falls on the surface of a piece of chromium in an evacuated glass tube. If the work function of chromium is $7.21\times \text{1}{0}^{-\text{19}}\text{J}$ , determine

(a) the maximum kinetic energy of the emitted photoelectrons and (b) the speed of photoelectrons that have this maximum kinetic energy.