Heat and Mass Transfer Emissivity of a white polished body in comparison to a black body is Depends upon the shape of body Lower Same Higher Depends upon the shape of body Lower Same Higher ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Thermal conductivity of glass wool varies from sample to sample because of variation in Porosity Composition Density All of these Porosity Composition Density All of these ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The value of the wavelength for maximum emissive power is given by Planck's law Wien’s law Stefan's law Fourier's law Planck's law Wien’s law Stefan's law Fourier's law ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Heat conducted through per unit area and unit thick face per unit time when temperature difference between opposite faces is unity, is called Temperature gradient Thermal coefficient Thermal conductivity Thermal resistance Temperature gradient Thermal coefficient Thermal conductivity Thermal resistance 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 = [2π (T₁ - T₂)]/2.3 lk log (r₂/r₁) Q = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁) Q = = 2πlk/2.3 (T₁ - T₂) log (r₂/r₁) Q = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)] Q = [2π (T₁ - T₂)]/2.3 lk log (r₂/r₁) Q = [2πlk (T₁ - T₂)]/2.3 log (r₂/r₁) Q = = 2πlk/2.3 (T₁ - T₂) log (r₂/r₁) Q = 2.3 log (r₂/r₁)/[2πlk (T₁ - T₂)] ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Which of the following is a case of steady state heat transfer? None of these Heating of building in winter I.C. engine Air preheaters None of these Heating of building in winter I.C. engine Air preheaters ANSWER DOWNLOAD EXAMIANS APP
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