Question

The wavelengths of two photons are $2000\mathring{A}$ and $4000\mathring{A}$ respectively. What is the ratio of their energies?

• A. $1/4$
• B. $4$
• C. $1/2$
• D. $2$

Answer 1

Answer: (D)

$E_1=h.\frac{c}{{\lambda }_1};E_2=h.\frac{c}{{\lambda }_2}$
$\frac{E_1}{E_2}=\frac{hc}{{\lambda }_1}\times \frac{{\lambda }_2}{hc}=\frac{{\lambda }_2}{{\lambda }_1}=\frac{4000}{2000}=2$