Question

Calculate the energy of photon of light having frequency 3 × 10¹⁵ Hz. If the wavelength of the light is (0.50 Å), then calculate its energy.

Answer 1

(i) Energy (E) of a photon is given by the expression,
E = hv
Where, h = Planck’s constant = 6.626 × 10^-34 Js
v = frequency of light = 3 × 10¹⁵ Hz (Given) Substituting the values we get,
E = (6.626 × 10^-34) × (3 × 10¹⁵)
E = 1.988 × 10^-18 J

(ii) Energy (E) of a photon having wavelength (λ) is given by the expression,
Where, E = \(\frac{h c}{\lambda}\)
h = Planck’s constant = 6.626 × 10^-34 Js
c = velocity of light in vacuum = 3 × 10⁸ m/sec
X = wavelength = 0.50 A or 0.50 × 10^-10 m
Substituting values in expression we get,
= 6.626 × 10^-34 × 3 × 10⁸/ 0.50 × 10^-10
= 3.98 × 10^-15 J