Heat and Mass Transfer Absorptivity of a body will be equal to its emissivity At all temperatures At one particular temperature At critical temperature When system is under thermal equilibrium At all temperatures At one particular temperature At critical temperature When system is under thermal equilibrium ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The heat transfer from a hot body to a cold body is directly proportional to the surface area and difference of temperatures between the two bodies. This statement is called Newton's law of cooling Newton's law of heating Stefan's law First law of thermodynamics Newton's law of cooling Newton's law of heating Stefan's law First law of thermodynamics ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The critical radius is the insulation radius at which the resistance to heat flow is Zero Minimum None of these Maximum Zero Minimum None of these Maximum ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Kirchhoff's law states that The total radiation from a black body per second per unit area is directly proportional to the fourth power of the absolute temperature The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body The wave length corresponding to the maximum energy is proportional to the absolute temperature None of these The total radiation from a black body per second per unit area is directly proportional to the fourth power of the absolute temperature The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body The wave length corresponding to the maximum energy is proportional to the absolute temperature None of these ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The process of heat transfer from one particle of the fluid to another by the actual movement of the fluid particles caused by some mechanical means, is known as Radiation Forced convection Conduction Free convection Radiation Forced convection Conduction Free convection ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The heat transfer by conduction through a thick cylinder (Q) is given by (where T₁ = Higher temperature, T₂ = Lower temperature, r₁ = Inside radius, r₂ = Outside radius, l = Length of cylinder, and k = Thermal conductivity) Q = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁) Q = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)] Q = [2π (T₁ - T₂)]/2.3 lk log (r₂/r₁) Q = = 2πlk/2.3 (T₁ - T₂) log (r₂/r₁) Q = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁) Q = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)] Q = [2π (T₁ - T₂)]/2.3 lk log (r₂/r₁) Q = = 2πlk/2.3 (T₁ - T₂) log (r₂/r₁) ANSWER DOWNLOAD EXAMIANS APP
EXAMIANS