Light and Matter

When light strikes a material, it can cause a number of effects, depending upon the nature of the material and the characteristics of the light. Light can be thought of as packets of energy (photons) which can be described in terms of their wavelengths or frequencies. When the energy reaches matter, it can cause effects to the nucleus or the electrons that surround it. This is manifested by the absorption of certain wavelengths of the light. The exact wavelengths of light absorbed are characteristic of the material and the molecules from which it is made. This information helps to characterize materials.