Question

The photon energy in units of $eV$ for electromagnetic waves of wavelength $2cm$ is

• A. $2.5\times 10^{-19}$
• B. $5.2\times 10^{16}$
• C. $3.2\times 10^{-16}$
• D. $6.2\times 10^{-5}$

Answer 1

Answer: (D)

As $E=\frac{hc}{\lambda }$
$=\frac{6.6\times 10^{-34}\times 3\times 10^8}{2\times 10^{-2}}$
$=9.9\times 10^{-24}J$
$=\frac{9.9\times 10^{-24}}{1.6\times 10^{-19}}eV$
$=6.2\times 10^{-5}eV$