The ratio of heat flow Q1/Q2 from two walls of same thickness having their thermal conductivities as ATj – 2K2 will be ________________?

A. I
B. 0.5
C. 2
D. 0.25

Thermal diffusivity of a substance is ____________________?

A. Proportional of thermal conductivity
B. Inversely proportional to k
C. Proportional to (k)
D. Inversely proportional to k2

According to Prevost theory of heat exchange ___________________?

A. It is impossible to transfer heat from low temperature source to t high temperature source
B. Heat transfer by radiation requires no medium
C. All bodies above absolute zero emit radiation
D. Heat transfer in most of the cases takes place by combination of conduction, convection and radiation

Thermal conductivity of glass-wool varies from sample to sample because of variation in ________________ ?

A. composition
B. density
C. porosity
D. structure

Which of the following has least value of conductivity_________________?

A. glass
B. water
C. plastic
D. rubber

Heat flows from one body to other when they have_________________?

A. Different heat contents
B. Different specific heat
C. Different atomic structure
D. Different temperatures

The amount of heat flow through a body by conduction is_______________?

A. directly proportional to the surface area of the body
B. directly proportional to the temperature difference on the two faces of the body
C. dependent upon the material of the body
D. inversely proportional to the thickness of the body

Which of the following has maximum value of thermal conductivity________________?

A. Aluminium
B. Steel
C. Brass
D. Copper

Heat transfer by radiation mainly depends upon___________________?

A. Its temperature
B. Nature of the body
C. Kind and extent of its surface
D. All of the above

Moisture would find its way into insulation by vapour pressure unless it is prevented by __________________ ?

A. High thickness of insulation
B. High vapour pressure
C. Less thermal conductivity insulator
D. A vapour seal