A. a dimensionless parameter
B. function of temperature
C. used as mathematical model
D. a physical property of the material
E. useful in case of heat transfer by radiation
A. high thickness of insulation
B. high vapour pressure
C. less thermal conductivity insulator
D. a vapour seal
E. all of the above
A. its temperature
B. nature of the body
C. kind and extent of its surface
D. all of the above
E. none of the above
A. aluminium
B. steel
C. brass
D. copper
E. lead
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
E. all of the above
A. different heat contents
B. different specific heat
C. different atomic structure
D. different temperatures
E. none of the above
A. glass
B. water
C. plastic
D. rubber
E. air
A. composition
B. density
C. porosity
D. structure
E. all of the above
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
E. rate of heat transfer depends on thermal conductivity and temperature difference
A. proportional of thermal conductivity
B. inversely proportional to k
C. proportional to (k)
D. inversely proportional to k2
E. none of the above