2.6 Find the energy of each of the photons which

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

(ii) have a wavelength of 0.50 Å.

(i) Energy (E) of a photon is given by the expression,
E = hv
Where, h = Planck’s constant = 6.626 × 10-34 Js
ν = frequency of light = 3 × 1015 Hz
Substituting the values in the given expression of E:
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,
E=hcλ
h = Planck’s constant = 6.626 × 10-34 Js
c = velocity of light in vacuum = 3 × 108 m/s
Substituting the values in the given expression of E:

E=6.626x10-343x1080.50x10-10=3.976x10-15J
E=3.98x10-15J