Question

Calculate the wavelength, wave number and frequency of photon having an energy equal to three electron volt. $(h=6.62\times {10}^{-27}ergsec.)$.

Answer 1

We know that,
$E=h\cdot v$
$v=\frac{E}{h}$ $(1eV=1.602\times {10}^{-12}erg)$
$=\frac{3\times (1.602\times {10}^{-12})}{6.62\times {10}^{-27}}$
$=7.26\times {10}^{14}{s}^{-1}$
$=7.26\times {10}^{14}Hz$
$\lambda =\frac{c}{v}=\frac{3\times {10}^{10}}{7.26\times {10}^{14}}=4.132\times {10}^{-5}cm$
$\overline{v}=\frac{1}{\lambda }=\frac{1}{4.132\times {10}^{-5}}=2.42\times {10}^4{cm}^{-1}$.