Question

Calculate the energy in joule of a photon of wavelength $4000\mathring{A}$

Answer 1

We know $E=hc/\lambda$

$=6.626\times {10}^{-34}\times 3\times {10}^8/4000\times {10}^{-10}$

$=4.96\times {10}^{-19}J$