Heat and Mass Transfer 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. This statement is known as Wien's law Planck's law Stefan's law Kirchhoff's law Wien's law Planck's law Stefan's law Kirchhoff's law ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The critical thickness of insulation for a sphere is h₀/2k 2k/h₀ k/h₀ h₀/k h₀/2k 2k/h₀ k/h₀ h₀/k ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The total emissivity power is .defined as the total amount of radiation emitted by a black body per unit Thickness Time Temperature Area Thickness Time Temperature Area 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) P = 0, x = 0 and a = 1 P = 0, x = 1 and a = 0 X = 0, a + p = 1 P=1, T = 0 and a = 0 P = 0, x = 0 and a = 1 P = 0, x = 1 and a = 0 X = 0, a + p = 1 P=1, T = 0 and a = 0 ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer When absorptivity (α) = 1, reflectivity (ρ) = 0 and transmissivity (τ) = 0, then the body is said to be a White body Opaque body Black body Grey body White body Opaque body Black body Grey body ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer The thermal diffusivities for gases are generally More than those for solids Less than those for liquids More than those for liquids Dependent on the viscosity More than those for solids Less than those for liquids More than those for liquids Dependent on the viscosity ANSWER DOWNLOAD EXAMIANS APP
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