All radiations in a black body are___________________?

A. Reflected
B. Refracted
C. Transmitted
D. Absorbed

The unit of overall coefficient of heat transfer is___________________?

A. Kcal/m2
B. Kcal/hr °c
C. Kcal/m2 hr °c
D. Kacl/m hr °c

The value of the wavelength for maximum emissive power is given by ___________________?

A. Wien’s law
B. Planck’s law
C. Stefan’s law
D. Fourier’s law

Total emissivity of polished silver compared to black body is___________________?

A. Same
B. Higher
C. More or less same
D. Very much lower

The value of Prandtl number for air is about _______________________?

A. 0.1
B. 0.3
C. 0.7
D. 1.7

The energy distribution of an ideal reflector at higher temperatures is largely in the range of ___________________?

A. Shorter wavelength
B. Longer wavelength
C. Remains same at all wavelengths
D. Wavelength has nothing to do with it

Which of the following property of air does not increase with rise in temperature ________________?

A. Thermal conductivity
B. Thermal diffusivity
C. Density
D. Dynamic viscosity

In free con-vection heat transfer, Nusselt number is function of________________?

A. Grashoff no. and reynold no
B. Grashoff no and prandtl no.
C. Prandtl no. and reynold no
D. Grashoff no., prandtl no and reynold no

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

A. Absolute temperature
B. Square of temperature
C. Fourth power of absolute temperature
D. Fourth power of temperature

Log mean temperature difference in case of counter flow compared to parallel flow will be________________?

A. Same
B. More
C. Less
D. Depends on other factors