Question

Find the energy of each of the photons which (i) corresponds to light of frequency 3×1015 Hz. (ii) have a wavelength of 0.50 Å

Answer 1

(i) Energy (E) of a photon is given by the expression, E = hv
Where, h = Planck's constant = 6.626 × 1034 Js
frequency of light = 3 × 1015Hz
Substituting the values in the given expression of E:
E = (6.626 × 1034) (3 × 1015)
E = 1.988 × 1018 J
(ii) Energy (E) of a photon having wavelength is given by the expression, E = $\frac{hc}{\lambda}$
h = Planck's constant = 6.626 × 1034 Js
c = velocity of light in vacuum = 3×108m/s
Substituting the values in the given expression of E:
E = $\frac{(6.626\times 10^{-34})(3\times10^8)}{0.50\times10^{-10}}$ = 3.976 × 10-15 J
∴ E = 3.98 × 10-15 J