Heat and Mass Transfer The value of the wave length for maximum emissive power is given by Planck’s law Stefan’s law Kirchhoff’s law Wine’s law Planck’s law Stefan’s law Kirchhoff’s law Wine’s law 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 Four Two One Three Four Two One Three ANSWER DOWNLOAD EXAMIANS APP
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 Kirchhoff's law Wien's law Planck's law Stefan's law Kirchhoff's law Wien's law Planck's law Stefan's law ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer In free convection heat transfer transition from laminar to turbulent flow is governed by the critical value of the Prandtl number, Grashoff's number Grashoff's number Reynold's number Reynold's number, Grashoff's number Prandtl number, Grashoff's number Grashoff's number Reynold's number Reynold's number, Grashoff's number ANSWER DOWNLOAD EXAMIANS APP
Heat and Mass Transfer Thermal conductivity of air with rise in temperature Decreases Increases Remain constant May increase or decrease depending on temperature Decreases Increases Remain constant May increase or decrease depending on temperature 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 Opaque body Black body White body Grey body Opaque body Black body White body Grey body ANSWER DOWNLOAD EXAMIANS APP
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