Problem 5.276

Find the maximum kinetic energy of photoelectrons liberated from the surface of lithium by electromagnetic radiation whose electric component varies with time as $E=a(1+\cos \omega t) \cos \omega_{0} t,$ where $a$ is a constant, $\omega=6.0 \cdot 10^{14} \mathrm{~s}^{-1}$ and $\omega_{0}=3.60 \cdot 10^{15} \mathrm{~s}^{-1}$