## University Physics with Modern Physics (14th Edition)

a. The energy requirement matches the energy of the maximum-wavelength photon. $$E= hf=h\frac{c}{\lambda}$$ $$\lambda =\frac{hc}{E}=\frac{1.24\times10^{-6}eV\cdot m}{0.67eV}=1.85\times10^{-6}m$$ b. $$E= hf=h\frac{c}{\lambda}$$ $$\lambda =\frac{hc}{E}=\frac{1.24\times10^{-6}eV\cdot m}{1.12eV}=1.11\times10^{-6}m$$