Question

The energy of incident photons corresponding to maximum wavelength of visible light is

• A. 3.2 eV
• B. 7 eV
• C. 1.55 eV
• D. 1 eV

Answer 1

Answer: (C)

From Planck's hypothesis, the energy of a photon, of frequency vis $E=hv=\frac{hc}{\lambda }$
where $c$ is speed of light and $a$. the wavelength.
In the visible part, red colour has maximum wavelength $\lambda =8000\mathring{A}$
$\therefore E=\frac{6.6\times 10^{-34}\times 3\times 10^8}{8000\times 10^{-10}}$
Also, $1eV=1.6\times 10^{-19}J$
$\therefore E=\frac{6.6\times 10^{-34}\times 3\times 10^8}{8000\times 10^{-10}\times 1.6\times 10^{-19}}=1.547eV$