RADIATION Flashcards
The process of converting radiation intercepted by matter to internal thermal energy
Absorption
Fraction of the incident radiation absorbed by matter. Modifiers: deirectional, hemisphirical, spectral, total
Absorptivity
The ideal emitter and absorber. Modifier referring to ideal behavior. Denoted by the subscript b.
blackbody
Modifier referring to the directional independence of the intensity associated with emitted, reflected, or incident radiation
Diffuse
Modifier refeering to a particular direction. Denoted by the subscript theta.
Directional
refers to variation with direction
directional distribution
The process of radiation production by matter at a finite temperature. Modifiers: diffuse, blackbody, spectral
Emission
Rate of radiant energy emitted by a surface in all directions per unit area of the surface, E(W/m2). Modifiers: spectral, total, blackbody
Emissive power
Ratio of the radiation emitted by a surface to the radiation emitted by a blackbody at the same termperature . Modifiers: directional, hemispherical, spectral, total
Emissivity
A surface for which the spectral absorptivity and the emissivity are independent of wavelength over the spectral regions of surface irradiation and emission.
Gray Surface
Modifier referring to all directions in the space above a surface
Hemisphirical
Rate of radiant energy propagation in a particular direction, per unit area normal to the ddirection, per unit solid anglle about the direction, I(W/m2 x sr). Modifier: spectral
Intensity
Rate at which radiation is incident on a surface from all directions per unit are of the surface. Modifiers: spectral, total, diffuse
Irradiation
Relation between emission and absorption properties for surfaces irradiated by a blackbody at the same temeperature
Kurchoff’s Law
Spectral distribution of emission from a blackbody
Planck’s law
Rate at which radiation leaves a surface due to emission and reflection in all directions per unit area of the surface, J(W/m2) Modifiers: spectral, total
Radiosity
The process of redirection of radiation incident on a surface. Modifiers:: diffuse, specular
Reflection
Fraction of the incident radiation reflected by matter. Modifiers: directional, hemispherical, spectral, total
Reflectivity
Refers to a medium in which radiation absorption is a volumetric process
Semitransparent
Region subtended by an element if area on the surface of a sphere with respect to the center of the sphere, w(sr)
Solid Angle
Modifier referring to a single-wavelength (nonchromatic)
component
Spectral
