emissive power การใช้

• That universal function describes the perfect black-body emissive power ."
• In some cases, emissive power and absorptivity may be defined to depend on angle, as described below.
• Kirchhoff's great insight was to recognize the universality and uniqueness of the function that describes the black body emissive power.
• Then for a perfectly black body, the wavelength-specific ratio of emissive power to absorption ratio is again just, with the dimensions of power.
• Then for a perfectly black body, the wavelength-specific ratio of emissive power to absorption ratio } } is again just, with the dimensions of power.
• The effective temperature of the Sun ( 5777 K ) is the temperature a black body of the same size must have to yield the same total emissive power.
• A perfect black body in thermodynamic equilibrium absorbs all light that strikes it, and radiates energy according to a unique law of radiative emissive power for temperature, universal for all perfect black bodies.
• Prior to Kirchhoff's studies, it was known that for total heat radiation, the ratio of emissive power to absorptive ratio was the same for all bodies emitting and absorbing thermal radiation in thermodynamic equilibrium.
• His proof first argued that for wavelength and at temperature, at thermal equilibrium, all perfectly black bodies of the same size and shape have the one and the same common value of emissive power, with the dimensions of power.
• :" For a body of any arbitrary material emitting and absorbing thermal electromagnetic radiation at every wavelength in thermodynamic equilibrium, the ratio of its emissive power to its dimensionless coefficient of absorption is equal to a universal function only of radiative wavelength and temperature.
• The law states that the total energy radiated per unit surface area of a black body across all wavelengths per unit time ( also known as the black-body radiant exitance or emissive power ) is directly proportional to the fourth power of the body's absolute temperature.
• In slightly different terms, the emissive power of an arbitrary opaque body of fixed size and shape at a definite temperature can be described by a dimensionless ratio, sometimes called the emissivity, the ratio of the emissive power of the body to the emissive power of a black body of the same size and shape at the same fixed temperature.
• In slightly different terms, the emissive power of an arbitrary opaque body of fixed size and shape at a definite temperature can be described by a dimensionless ratio, sometimes called the emissivity, the ratio of the emissive power of the body to the emissive power of a black body of the same size and shape at the same fixed temperature.
• In slightly different terms, the emissive power of an arbitrary opaque body of fixed size and shape at a definite temperature can be described by a dimensionless ratio, sometimes called the emissivity, the ratio of the emissive power of the body to the emissive power of a black body of the same size and shape at the same fixed temperature.
• Thus Kirchhoff's law of thermal radiation can be stated : " For any material at all, radiating and absorbing in thermodynamic equilibrium at any given temperature, for every wavelength, the ratio of emissive power to absorptive ratio has one universal value, which is characteristic of a perfect black body, and is an emissive power which we here represent by . " ( For our notation, Kirchhoff's original notation was simply .)
• Thus Kirchhoff's law of thermal radiation can be stated : " For any material at all, radiating and absorbing in thermodynamic equilibrium at any given temperature, for every wavelength, the ratio of emissive power to absorptive ratio has one universal value, which is characteristic of a perfect black body, and is an emissive power which we here represent by . " ( For our notation, Kirchhoff's original notation was simply .)
• Thus "'Kirchhoff's law of thermal radiation "'can be stated : " For any material at all, radiating and absorbing in thermodynamic equilibrium at any given temperature " ", for every wavelength " ", the ratio of emissive power to absorptive ratio has one universal value, which is characteristic of a perfect black body, and is an emissive power which we here represent by " " . " ( For our notation, Kirchhoff's original notation was simply .)
• Thus "'Kirchhoff's law of thermal radiation "'can be stated : " For any material at all, radiating and absorbing in thermodynamic equilibrium at any given temperature " ", for every wavelength " ", the ratio of emissive power to absorptive ratio has one universal value, which is characteristic of a perfect black body, and is an emissive power which we here represent by " " . " ( For our notation, Kirchhoff's original notation was simply .)