Question

Find energy of each of the photons which

(i) Correspond to light of frequency 3 x 10¹⁵ Hz.

(ii) Have wavelength of 0.50 Å.

Answer 1

Energy of a photon of light of frequency v is given by hv and that having wavelength λ is hc/λ,

(i) Energy of photon of light having the frequency of 3 x 10¹⁵ Hz

= hv = 6.626 x 10^-34 Js x 3 x 10¹⁵ s^-1

= 1.988 10^-18 J

(ii) Energy of photon of light having wavelength of 0.5 Å

= hc/λ = {6.626 x 10^-34 Js x 3 x 10⁸ ms^-1}/{0.5 x 10^-10 m}

= 3.98 x 10^-15 J