Question

Two photons have energies of $4.95\times {10}^{-19}$J and $14.85\times {10}^{-19}$J. Then the ratio of their wavelengths is

• A. 1 : 3
• B. 3 : 1
• C. 1 : 2
• D. 1 : 4

Answer 1

Answer: (B)

3 : 1

energy (E) $=\frac{hc}{\lambda }$

So, $\frac{E_1}{E_2}=\frac{{\lambda }_2}{{\lambda }_1}$

or $\frac{{\lambda }_1}{{\lambda }_2}=\frac{E_2}{E_1}$

$=\frac{14.85\ast {10}^{-19}}{4.95\ast {10}^{-19}}$

$=\frac{3}{1}$

So, the answer is option (B).