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
Related Mcqs:
- 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
E. none of the above - Unit of thermal diffusivity is_________________?
A. m2/hr
B. m2/hr°C
C. kcal/m2 hr
D. kcal/m.hr°C
E. kcal/m2 hr°C - Thermal diffusivity of a substance is __________________?
A. directly proportional to thermal con¬ductivity
B. inversely proportional to density of substance
C. inversely proportional to specific heat
D. all of the above
E. none of the above - Thermal conductivity of water in general with rise in temperature ____________________?
A. increases
B. decreases
C. remains constant
D. may increase or decrease depending on temperature
E. none of the above - Thermal conductivity of non-metallic amorphous solids with decrease in temperature __________________?
A. increases
B. decreases
C. remains constant
D. may increase or decrease depending on temperature
E. unpredictable - Unit of thermal conductivity in M.K.S. units is ___________________?
A. kcal/kg m2 °C
B. kcal-m/hr m2 °C
C. kcal/hr m2 °C
D. kcal-m/hr °C
E. kcal-m/m2 °C - Thermal conductivity of air at room temperature in kcal/m hr °C is of the order of__________________?
A. 0.002
B. 0.02
C. 0.01
D. 0.1
E. 0.5 - Which of the following is expected to have highest thermal conductivity_______________?
A. steam
B. solid ice
C. melting ice
D. water
E. boiling water - Thermal conductivity of glass-wool varies from sample to sample because of variation in ________________ ?
A. composition
B. density
C. porosity
D. structure
E. all of the above - The thermal diffusivities for gases are generally_____________________?
A. more than those for liquids
B. less than those for liquids
C. more than those for solids
D. dependent on the viscosity
E. same as for the liquids
