Heat and Mass Transfer A composite slab has two layers of different materials with thermal conductivities k₁ and k₂. If each layer has the same thickness, then the equivalent thermal conductivity of the slab will be 2 k₁ k₂/ (k₁ + k₂) (k₁ + k₂)/ k₁ k₂ (k₁ + k₂) k₁ k₂ 2 k₁ k₂/ (k₁ + k₂) (k₁ + k₂)/ k₁ k₂ (k₁ + k₂) k₁ k₂ ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The rate of heat flow through a body is Q = [kA (T₁ - T₂)]/x. The term x/kA is known as Thermal conductivity Thermal coefficient Thermal resistance None of these Thermal conductivity Thermal coefficient Thermal resistance None of these 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 Thermal coefficient Temperature gradient Thermal conductivity Thermal resistance Thermal coefficient Temperature gradient Thermal conductivity Thermal resistance ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Depending on the radiating properties, a body will be white when (Where a = absorptivity, p = reflectivity, x = transmissivity) X = 0, a + p = 1 P=1, T = 0 and a = 0 P = 0, x = 1 and a = 0 P = 0, x = 0 and a = 1 X = 0, a + p = 1 P=1, T = 0 and a = 0 P = 0, x = 1 and a = 0 P = 0, x = 0 and a = 1 ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Two long parallel surfaces each of emissivity 0.7 are maintained at different temperatures and accordingly have radiation heat exchange between them. It is desired to reduce 75% of the radiant heat transfer by inserting thin parallel shields of emissivity 1 on both sides. The number of shields should be Three Two Four One Three Two Four One ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The value of the wavelength for maximum emissive power is given by Stefan's law Planck's law Fourier's law Wien’s law Stefan's law Planck's law Fourier's law Wien’s law ANSWER DOWNLOAD EXAMIANS APP
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