Photon Energy
The amount of energy is proportional to the photon’s electromagnetic frequency, so it is inversely proportional to the wavelength. The higher the frequency of the photon, the higher its energy. Therefore, the longer the photon’s wavelength, the lower its energy.
Photon Energy Formula
Photon Energy formula E(j) in joule is equal to the planck’s constant h(j/s) in joule per second and multiply the speed of the light c(m/s) in meter per second and divided by the wavelength of the light λ(N/m) in Newton per meter.Hence the photon Energy Formula can be written as
E(j)=h(j/s)* c(m/s)/ λ(N/m)
Where
E = photon energy in j
h = Planck’s constant (6.626×10−34 Js)
c = speed of the light in m/s
λ = wavelength of the light in Newton per meter
Photon Energy Calculation:
Example 1
Determine the photon energy if the wavelength is 850nm
Solution
Given parameters are
Λ =850nm
C=3×108×108 m/s
h=6.626×10-34 Js
Photon energy formula is given by
E=hc/ λ
E=6.626×10-34 ×3×108 /850×10-9
E=19.878 ×1028 / 850×10-9
E=2.3385×10-17 J
Example 2
If the energy of a photon is 750×10-10 J.determine the wavelength of that photon
Solution
Given parameters are
E=750×10-10 J
C=3×108×108 m/s
h=6.626×10-34Js
Photon energy formula is given by
E=hc/ λ
E=6.626×10-34 ×3×108 /750×10-10
E=19.878 ×10 -28 / 750×10-10
E= 2.649×10-16 m