Question

The ratio of the energies of photons of $2000\stackrel{0}{A}$ to that of $4000\stackrel{o}{A}$ is:

• A. $2$
• B. $4$
• C. $\frac{1}{2}$
• D. $\frac{1}{4}$

Answer 1

Answer: (A)

$2$

$E=\frac{hc}{\lambda }$
$\Rightarrow \lambda \propto \frac{1}{E}$
$\therefore \frac{{\lambda }_1}{{\lambda }_2}=\frac{E_2}{E_1}=\frac{4000\stackrel{o}{A}}{2000\stackrel{o}{A}}$
$\therefore {\lambda }_1:{\lambda }_2=2:1$