Heat transfer MCQ with Answers

66) Total emissivity of polished silver compared to black body is

Answer is:

very much lower

67) According to Stefan-Boltzmann law, ideal radiators emit radiant energy at a rate proportional to

Answer is:

fourth power of absolute temperature

Explanation:

According to Stefan's law, the total radiation from a black body per second per unit area is directly proportional to the fourth power of the absolute temperature. Stefan Boltzmann law is applicable for heat transfer by radiation. The unit of Stefan-Boltzman is Watt/m²K⁴.

68) Which of the following property of air does not increase with rise in temperature

Answer is:

density

69) The unit of Stefan Boltzmann constant is

Answer is:

watt/cm2 °K4

Explanation:

According to Stefan's law, the total radiation from a black body per second per unit area is directly proportional to the fourth power of the absolute temperature. Stefan Boltzmann law is applicable for heat transfer by radiation. The unit of Stefan-Boltzman is Watt/m²K⁴.

70) In free con-vection heat transfer, Nusselt number is function of

Answer is:

66) Total emissivity of polished silver compared to black body is

very much lower

67) According to Stefan-Boltzmann law, ideal radiators emit radiant energy at a rate proportional to

fourth power of absolute temperature

68) Which of the following property of air does not increase with rise in temperature

density

69) The unit of Stefan Boltzmann constant is

watt/cm2 °K4

70) In free con-vection heat transfer, Nusselt number is function of

Grashoff no. and Prandtl no.