Reflection involves a change in direction of waves when they bounce off a barrier. Refraction of waves involves a change in the direction of waves as they pass from one medium to another. Refraction, or the bending of the path of the waves, is accompanied by a change in speed and wavelength of the waves
Absorption is the transformation of radiant power to another type of energy, usually heat, by interaction with matter. The transmittance t of a medium is defined by the ratio of transmitted radiant power to incident radiant power.
