Stefan Boltzmann law is applicable for heat transfer by Radiation Conduction and radiation combined Convection Conduction TRUE ANSWER : ? YOUR ANSWER : ?
The process of heat transfer from one particle of the fluid to another by the actual movement of the fluid particles caused by some mechanical means, is known as Conduction Radiation Free convection Forced convection TRUE ANSWER : ? YOUR ANSWER : ?
40% of incident radiant energy on the surface of a thermally transparent body is reflected back. If the transmissivity of the body be 0.15, then the emissivity of surface is 0.75 0.55 0.45 0.4 TRUE ANSWER : ? YOUR ANSWER : ?
Thermal diffusivity is A physical property of the material A dimensionless parameter Function of temperature Used as mathematical model TRUE ANSWER : ? YOUR ANSWER : ?
Thermal conductivity of water at 20°C is of the order of 0.51 0.42 0.23 0.1 TRUE ANSWER : ? YOUR ANSWER : ?
If the temperature of a solid surface changes form 27°C to 627°C, then its emissive power changes in the ratio of 81 9 270 3 TRUE ANSWER : ? YOUR ANSWER : ?
The ratio of Nusselt number and the product of Reynold's number and Prandtl number is equal to Peclet number Stanton number Grashoff number Biot number TRUE ANSWER : ? YOUR ANSWER : ?
A grey body is one whose absorptivity Varies with wavelength of the incident ray Is equal to its emissivity Does not vary with temperature and. wavelength of the incident ray Varies with temperature TRUE ANSWER : ? YOUR ANSWER : ?
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 One Two Four TRUE ANSWER : ? YOUR ANSWER : ?
According to Wien's law, the wavelength corresponding to maximum energy is proportion to I² T Absolute temperature (T) F TRUE ANSWER : ? YOUR ANSWER : ?