# Find energy of each of the photons which

Question.

Find energy of each of the photons which

(i)correspond to light of frequency 3× 1015 Hz.

(ii)have wavelength of 0.50 Å. [/question

Solution:

(i) Energy $(E)$ of a photon is given by the expression,

$E=h v$

Where, $h=$ Planck's constant $=6.626 \times 10^{-34} \mathrm{Js}$

$v=$ frequency of light $=3 \times 10^{15} \mathrm{~Hz}$

Substituting the values in the given expression of $E$ :

$E=\left(6.626 \times 10^{-34}\right)\left(3 \times 10^{15}\right)$

$E=1.988 \times 10^{-18} \mathrm{~J}$

(ii) Energy $(E)$ of a photon having wavelength $(\lambda)$ is given by the expression,

$E=\frac{\text { hc }}{\lambda}$

$\mathrm{h}=$ Planck's constant $=6.626 \times 10^{-34} \mathrm{Js}$

$c=$ velocity of light in vacuum $=3 \times 10^{8} \mathrm{~m} / \mathrm{s}$

Substituting the values in the given expression of $E$ :

$E=\frac{\left(6.626 \times 10^{-34}\right)\left(3 \times 10^{8}\right)}{0.50 \times 10^{-10}}=3.976 \times 10^{-15} \mathrm{~J}$

$\therefore E=3.98 \times 10^{-15} \mathrm{~J}$