1) The wavelengths of the two photons are 2000Å and 4000Å respectively. What is the ratio of their energies? A) 1/4 B) 4 C) 1/2 D) 2 Answer: Option DExplanation:$E_{1}=h.\frac{c}{\lambda_{1}}$; $E_{2}=h.\frac{c}{\lambda_{2}}$ $\frac{E_{1}}{E_{2}} = \frac{hc}{\lambda_{1}}\times\frac{\lambda_{2}}{hc}$ = $\frac{\lambda_{2}}{\lambda_{1}}$ = $\frac{4000}{2000}$ = 2
