Answer: By a factor of 1/3.
Explanation:
For a photon with wavelength λ, the energy is written as:
E = h*c/λ
where:
h is the Planck's constant:
h = 6.63*10^(-34) Js
c is the speed of light:
c = 3*10^8 m/s
Now, if we triple the wavelength of this photon, then the energy will be:
E' = (h*c)/(3*λ)
We rewrite this as:
E' = (1/3)*(h*c/λ)
And (h*c/λ) was the previous energy:
(h*c/λ) = E
Then we can replace that in the above equation to get:
E' = (1/3)*(h*c/λ) = (1/3)*E
Then if we triple the wavelength, it will change the energy content of the individually radiated photons by a factor of 1/3.
