Question

The energy of a photon of light of wavelength $450nm$ is :

• A. $4.4\times 10^{-19}J$
• B. $2.5\times 10^{-19}J$
• C. $1.25\times 10^{-17}J$
• D. $2.5\times 10^{-17}J$

Answer 1

Answer: (A)

$E_{ph}=\frac{1240}{\lambda (\text{in}nm)}eV=\frac{1240}{450}\times 1.6\times {\left(10\right)}^{-19}=4.41\times {\left(10\right)}^{-19}J$