A white-light source radiates of power equally in two discrete spectral lines: violet…
PHYSICS · Subjective · A Level · Physics · Particles and radiation · Particles and radiation
Problem
A white-light source radiates 20W of power equally in two discrete spectral lines: violet light of wavelength 400nm and infrared light of wavelength 800nm. Assume 100% conversion of electrical energy into these two monochromatic beams and negligible emission at other wavelengths.
(i) Show that the energy of a single violet photon is twice the energy of a single infrared photon.
(ii) Calculate the number of violet photons and the number of infrared photons emitted by the source per second.
(iii) What percentage of the total number of photons emitted per second belong to the violet line?