Question

Calculate the wavelength of a photon (in nm) of energy 1 eV.

• A. $\text{12400 nm}$
• B. $\text{12.4 nm}$
• C. $\text{1240 nm}$
• D. $\text{124000 nm}$

Answer 1

The correct option is C $\text{1240 nm}$

$\text{E}=1\text{eV}=1.602\times {10}^{-19}\text{J}$
$\text{E}=\text{h}\nu$

$\text{E}=\text{h}\frac{c}{\lambda }$

$\lambda =\text{h}\frac{c}{\text{E}}$

$\lambda =\frac{6.62\times {10}^{-34}\text{Js}\times 3\times {10}^8\text{m/s}}{1.602\times {10}^{-19}\text{J}}$

$\lambda =12.40\times {10}^{-7}\text{m}$

$\lambda =1240\text{nm}$