Question

The wavelength of light in the visible region is about $390nm$ for violet colour and about $760nm$ for red colour. The energy of photon in $eV$ at violet end is

• A. $2.32$
• B. $3.19$
• C. $1.42$
• D. $4.13$

Answer 1

Answer: (B)

$3.19$

Energy of the incident photon,
$E=h\nu -\frac{hc}{\lambda }$
For violet light, $\lambda =390nm$
$\therefore$ Incident photon energy,$E=\frac{6.63\times {10}^{-34}\times 3\times {10}^8}{390\times {10}^{-9}}$J
$=5.1\times 10-19J=\frac{5.1\times {10}^{-19}}{1.6\times {10}^{19}}eV=3.19eV$