Question

Calculate the wavelength of a photon having an energy of 3 eV. Take $h=6.6\times {10}^{-34}Js$

• A. $4.125\times {10}^3\stackrel{\circ }{A}$
• B. $4.125\times {10}^4\stackrel{\circ }{A}$
• C. $5.125\times {10}^3\stackrel{\circ }{A}$
• D. $7.125\times {10}^3\stackrel{\circ }{A}$

Answer 1

The correct option is A $4.125\times {10}^3\stackrel{\circ }{A}$

$1eV=1.6\times {10}^{-19}J$
From Planck's quantum theory, E = $\frac{hc}{\lambda }$
where E = energy of the photon
$\lambda$ = Wavelength of the photon
So, $\lambda =\frac{hc}{E}=\frac{6.6\times {10}^{-34}\times 3\times {10}^8}{3\times 1.6\times {10}^{-19}}$
$\lambda =4.125\times {10}^3\stackrel{\circ }{A}$