Stefan’s law

Stefan s law states that the total energy / radiated by a blackbody per unit time and area (power per unit area) varies as the fourth power of the absolute temperature ... 

Emissive power is the total radiative power leaving the surface of the fire per unit area and per unit time. Emissive power can be calculated by use of Stefan s law, which gives the radiation of a black body in relation to its temperature. Because the fire is not a perfect black body, the emissive power is a fraction (e) of the black body radiation ... 

Equation 10.30 is known as Stefan s Law(3). Thus the bulk flow enhances the mass transfer rate by a factor Cj/Cjj, known as the drift factor. The fluxes of the components are given in Table 10.1. 

It may be noted that equation 10.86 is identical to equation 10.30. (Stefan s Law) and. Stefan s law can therefore also be derived from Maxwell s Law of Diffusion. 

By comparing equation 10.89 with Stefan s Law (equation 10.30) the effective diffu-sivity of A in the mixture (/> ) is given by ... 

A qualitative interference that can be drawn from Stefan s law pertains to the effect of high absolute temperatures on the quantities of heat radiated. This aspect is of great practical importance. As the temperature of a body is raised above that of its surroundings, the amount of heat it can radiate to them increases at a phenomenal rate. 

The solar flux can be calculated via Stefan s law from the observed surface temperature of the Sun, and the level of radiation at a known distance is calculated via the inverse square law (Figure 7.6). 

Stefan s law). Multiplying Eq. (3.11) by p and integrating over solid angles again, one has... 

Steeping parameters, 15 528t Steep tanks, 15 527-528 Stefan-Boltzmann law, 19 131 Stefan-Maxwell equations, 1 43-46, 598 Stefan s law, 7 327 Steinhart-Hart equation, 24 451 Stellite 1... 

This equation is known as Stefan s Law. Integration between two points denoted by suffices 1 and 2 gives... 

In fact, any deviation from Stefan s law is an indication that the surface molecules are oriented differently from those in the bulk phase. This observation is useful in order to understand surface phenomena. 

Two large parallel plates with grey surfaces are situated 75 mm apart one has an emissivity of 0.8 and is at a temperature of 350 K and the other has an emissivity of 0.4 and is at a temperature of 300 K. Calculate the net rate of heat exchange by radiation per square metre taking the Stefan-Boltzmann constant as 5.67 x 10-8 W/m2 K4. Any formula (other than Stefan s law) which you use must be proved. 

In general, the value of 3D0 is derivable from Stefan s law which states that... 

This relation is called Stefan s law. It may be integrated to give... 

This relation is known as Stefan s law, and the induced convective flow described that enhance.s mass diffusion is called the Stefan flow. Noting that y, — P/P and C = P/RJT for an ideal gas mixture, the evaporation rate of spccie /4 can also be expressed a.s... 

C What is Stefan flow Write the expression for Stefan s law and indicate what each variable represents. 

A.7.4 Show that (a) the Rayleigh-Jeans law is a special case of Planck distribution law for the blackbody spectrum. Show also that (b) Stefan s law and (c) the Wein displacement law can be derived from Planck s distribution law. 

Without going beyond thermodynamics and the electromagnetic theory of light, we can deduce two laws regarding the way in which black body radiation (or, as it is also called, cavity radiation) depends on the temperature. Stefan s law (1879) states that the total emitted radiation is proportional to the fourth power of the temperature of the radiator the hotter the body, the more it radiates. Proceeding a step further, W. Wien found the displacement law (1893) which bears his name, and which states that the spectral distribution of the energy density is given by an equation of the form... 

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