the free energy design has some basic rules
shown below as the reflection of white surfaces and the absorbance of dark or vacuum.
from Wikipedia
date : 05,05,2017
time; 18:10
A black body 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."[1]
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:[2]
Transmission, absorption, and reflection[edit]A body's behavior with regard to thermal radiation is characterized by its transmission τ, absorption α, and reflection ρ.
The boundary of a body forms an interface with its surroundings, and this interface may be rough or smooth. A nonreflecting interface separating regions with different refractive indices must be rough, because the laws of reflection and refraction governed by the Fresnel equations for a smooth interface require a reflected ray when the refractive indices of the material and its surroundings differ.[20] A few idealized types of behavior are given particular names:
An opaque body is one that transmits none of the radiation that reaches it, although some may be reflected.[21][22] That is, τ=0 and α+ρ=1
A transparent body is one that transmits all the radiation that reaches it. That is, τ=1 and α=ρ=0.
A gray body is one where α, ρ and τ are uniform for all wavelengths. This term also is used to mean a body for which α is temperature and wavelength independent.
A white body is one for which all incident radiation is reflected uniformly in all directions: τ=0, α=0, and ρ=1.
For a black body, τ=0, α=1, and ρ=0. Planck offers a theoretical model for perfectly black bodies, which he noted do not exist in nature: besides their opaque interior, they have interfaces that are perfectly transmitting and non-reflective.[23]
Between the WHITE reflection and RED absorbance would be the PINK as the GRAY BODY.
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.[5][6] Construction of black bodies with emissivity as close to one as possible remains a topic of current interest.[7]
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.
shown below as the reflection of white surfaces and the absorbance of dark or vacuum.
from Wikipedia
date : 05,05,2017
time; 18:10
A black body 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."[1]
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:[2]
- 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.
Transmission, absorption, and reflection[edit]A body's behavior with regard to thermal radiation is characterized by its transmission τ, absorption α, and reflection ρ.
The boundary of a body forms an interface with its surroundings, and this interface may be rough or smooth. A nonreflecting interface separating regions with different refractive indices must be rough, because the laws of reflection and refraction governed by the Fresnel equations for a smooth interface require a reflected ray when the refractive indices of the material and its surroundings differ.[20] A few idealized types of behavior are given particular names:
An opaque body is one that transmits none of the radiation that reaches it, although some may be reflected.[21][22] That is, τ=0 and α+ρ=1
A transparent body is one that transmits all the radiation that reaches it. That is, τ=1 and α=ρ=0.
A gray body is one where α, ρ and τ are uniform for all wavelengths. This term also is used to mean a body for which α is temperature and wavelength independent.
A white body is one for which all incident radiation is reflected uniformly in all directions: τ=0, α=0, and ρ=1.
For a black body, τ=0, α=1, and ρ=0. Planck offers a theoretical model for perfectly black bodies, which he noted do not exist in nature: besides their opaque interior, they have interfaces that are perfectly transmitting and non-reflective.[23]
Between the WHITE reflection and RED absorbance would be the PINK as the GRAY BODY.
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.[5][6] Construction of black bodies with emissivity as close to one as possible remains a topic of current interest.[7]
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.