ABSTRACT
This chapter provides a brief revision of the main features of the electromagnetic spectrum, and some fundamental quantities that are employed to quantify the radiation. The main part of the chapter describes the blackbody radiation for later reference, starting with the radiative properties of a blackbody, and formulating the properties of thermal radiation, consisting of the spectral distribution of number of photons and their energy. Finally, the authors examine the main aspects of the solar spectrum, which is the energy source that we wish to utilize for the production of useful energy, and how it relates to the idealized blackbody spectrum. There are three classes of lamps for lighting: incandescent, discharge, and solid state. Incandescent lamps heat a filament that glows. Discharge lamps and white light-emitting diodes are based on the emission of ultraviolet or blue photons, either by gas ionization or by electroluminescence.
