To
determine the energy of a light that is being emitted, we
need a relation that would relate to the wavelength of the light. For this case, we use the equation E = hc/λ where h is the Planck's constant and c is the speed of light and λ is the wavelength of the light. Planck's constant is equal to 6.626x10^-34 m^2 kg/s and speed of light is 3x10^8 m/s. The wavelength is 445 nm or 445x10^-9 m.
Energy of one photon = 6.626 x 10^-34 m^2 kg/s (3 x 10^8 m/s) / 445 x 10^-9 = 4.47 x 10^-19 J
Therefore the energy of the light is 4.47 x 10^-19 J.
