Stellar Spectrum Characteristics and Black Body Radiation
... (Note: It has also been experimentally determined that the energy flux in joules per unit area per second from a radiating object is proportional to the fourth power of the object’s surface temperature. The proportionality constant is called the StefanBoltzman constant. The symbol used to denote it ...
... (Note: It has also been experimentally determined that the energy flux in joules per unit area per second from a radiating object is proportional to the fourth power of the object’s surface temperature. The proportionality constant is called the StefanBoltzman constant. The symbol used to denote it ...
qwk9
... B. Einstein received the Nobel Prize in Physics for explaining the photo-electric effect and the “particle” (photon) nature of light given by the law: E = hν C. Kepler’s laws can be used to describe the motion of planets around the Sun D. Hubble is credited with the discovery of the expansion of the ...
... B. Einstein received the Nobel Prize in Physics for explaining the photo-electric effect and the “particle” (photon) nature of light given by the law: E = hν C. Kepler’s laws can be used to describe the motion of planets around the Sun D. Hubble is credited with the discovery of the expansion of the ...
Today`s Objectives - RanelaghALevelPhysics
... Define the term blackbody. Sketch and describe how shape of black body curves change as temperature is increased. Use Wien’s displacement law to estimate blackbody temperature of sources. Use Stefan’s law to estimate area needed for sources to have same power output as the sun. Recap inver ...
... Define the term blackbody. Sketch and describe how shape of black body curves change as temperature is increased. Use Wien’s displacement law to estimate blackbody temperature of sources. Use Stefan’s law to estimate area needed for sources to have same power output as the sun. Recap inver ...
Questions on Black Body radiation and Wien`s Law
... 1. Given the wavelength of maximum intensity observed in the spectrum of each of the stars below , calculate their surface temperature. ...
... 1. Given the wavelength of maximum intensity observed in the spectrum of each of the stars below , calculate their surface temperature. ...
Black body
A black body (also blackbody) is an idealized physical body that absorbs all incident electromagnetic radiation, regardless of frequency or angle of incidence. A white body is one with a ""rough surface [that] reflects all incident rays completely and uniformly in all directions.""A black body in thermal equilibrium (that is, at a constant temperature) emits electromagnetic radiation called black-body radiation. 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 in thermal equilibrium has two notable properties:It is an ideal emitter: at every frequency, it emits as much energy as – or more energy than – any other body at the same temperature.It is a diffuse emitter: the energy is radiated isotropically, independent of direction.An approximate realization of a black surface is a hole in the wall of a large enclosure (see below). Any light entering the hole is reflected indefinitely or absorbed inside and is unlikely to re-emerge, making the hole a nearly perfect absorber. 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.Real materials emit energy at a fraction—called the emissivity—of black-body energy levels. By definition, a black body in thermal equilibrium has an emissivity of ε = 1.0. A source with lower emissivity independent of frequency often is referred to as a gray body.Construction of black bodies with emissivity as close to one as possible remains a topic of current interest.In astronomy, the radiation from stars and planets is sometimes characterized in terms of an effective temperature, the temperature of a black body that would emit the same total flux of electromagnetic energy.