Heat and Mass Transfer The total radiation from a black body per second per unit area is ________ fourth power of the absolute temperature. This statement is known as Stefan Boltzmann law. None of these Equal to Directly proportional to Inversely proportional to None of these Equal to Directly proportional to Inversely proportional to ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer According to Prevost theory of heat exchange All bodies above absolute zero emit radiation Heat transfer in most of the cases takes place by combination of conduction, convection and radiation It is impossible to transfer heat from low temperature source to t high temperature source Heat transfer by radiation requires no medium All bodies above absolute zero emit radiation Heat transfer in most of the cases takes place by combination of conduction, convection and radiation It is impossible to transfer heat from low temperature source to t high temperature source Heat transfer by radiation requires no medium ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer 40% of incident radiant energy on the surface of a thermally transparent body is reflected back. If the transmissivity of the body be 0.15, then the emissivity of surface is 0.55 0.75 0.45 0.4 0.55 0.75 0.45 0.4 ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Fourier's law of heat conduction is (where Q = Amount of heat flow through the body in unit time, A = Surface area of heat flow, taken at right angles to the direction of heat flow, dT = Temperature difference on the two faces of the body, dx = Thickness of the body, through which the heat flows, taken along the direction of heat flow, and k = Thermal conductivity of the body) (dT/dx) k. k. k. (dx/dT) k. (dT/dx) (dx/dT) (dT/dx) k. k. k. (dx/dT) k. (dT/dx) (dx/dT) ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Metals are good conductors of heat because Their atoms collide frequently Their atoms are relatively far apart They contain free electrons They have high density Their atoms collide frequently Their atoms are relatively far apart They contain free electrons They have high density ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer A cube at high temperature is immersed in a constant temperature bath. It loses heat from its top, bottom and side surfaces with heat transfer coefficients of h₁, h₂ and h₃ respectively. The average heat transfer coefficient for the cube is 1/h₁ + 1/h₂ + 1/h₃ h₁ + h₂ + h₃ (h₁.h₂.h₃)1/3 None of these 1/h₁ + 1/h₂ + 1/h₃ h₁ + h₂ + h₃ (h₁.h₂.h₃)1/3 None of these ANSWER DOWNLOAD EXAMIANS APP
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