The total radiation from a black body per second per unit area is ________ fourth power of the absolute temperature. This statement is known as Stefan Boltzmann law. Inversely proportional to Equal to Directly proportional to None of these TRUE ANSWER : ? YOUR ANSWER : ?
According to Kirchoff's law, the ratio of emissive power to absorptivity for all bodies is equal to the emissive power of a Grey body Brilliant white polished body Black body Red hot body TRUE ANSWER : ? YOUR ANSWER : ?
Wien’s law states that the wave length corresponding to ________ is proportional to the absolute temperature. Minimum energy Maximum energy Both (A) and (B) None of these TRUE ANSWER : ? YOUR ANSWER : ?
Free convection flow depends on Density Gravitational force All of these Coefficient of viscosity TRUE ANSWER : ? YOUR ANSWER : ?
Heat is transferred by all three modes of transfer, viz. conduction, convection and radiation in Steam condenser Electric heater Boiler Refrigerator condenser coils TRUE ANSWER : ? YOUR ANSWER : ?
The ratio of surface convection resistance to the internal conduction resistance is known as Stanton number Biot number Prandtl number Grashoff number TRUE ANSWER : ? YOUR ANSWER : ?
According to Stefan Boltzmann law, ideal radiators emit radiant energy at a rate proportional to Fourth power of temperature Absolute temperature Fourth power of absolute temperature Square of temperature TRUE ANSWER : ? YOUR ANSWER : ?
An electric cable of aluminium conductor (k = 240 W/mK) is to be insulated with rubber (k = 0.15 W/mK). The cable is to be located in air (h = 6 W/m²). The critical thickness of insulation will be 25 mm 800 mm 160 mm 40 mm TRUE ANSWER : ? YOUR ANSWER : ?
The ratio of the thickness of thermal boundary layer to the thickness of hydrodynamic boundary layer is equal to (Prandtl number) n, where n is equal to =-1/3 -1 =-2/3 1 TRUE ANSWER : ? YOUR ANSWER : ?