![]() īLACKBODY RADIATION Introduction A \black body" is an object that absorbs all. Physics Course/Radiation/Black Body Radiation. EPA's Radiation Education Activities are designed to help increase awareness and. Preface The mystery of blackbody radiation triggered the birth of modern physics in 1900, when Planck in an \act of despair" invented the idea of a smallest. By definition, a black body in thermal equilibrium has an emissivity of. The radiation confined in such an enclosure may or may not be in thermal equilibrium, depending upon the nature of the walls and the other contents of the enclosure. Any light entering the hole is reflected indefinitely or absorbed inside and is unlikely to re- emerge, making the hole a nearly perfect absorber. An ideal black body in thermal equilibrium has two notable properties. The radiation is emitted according to Planck's law, meaning that it has a spectrum that is determined by the temperature alone (see figure at right), not by the body's shape or composition. A black body is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. Shown for comparison is the classical Rayleigh–Jeans law and its ultraviolet catastrophe. As the temperature of a black body decreases, its intensity also decreases and its peak moves to longer wavelengths. ![]()
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. ArchivesCategories |