A. m2/hr
B. m2/hr°C
C. kcal/m2 hr
D. kcal/m.hr°C
E. kcal/m2 hr°C
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 - Thermal diffusivity is ____________________?
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 - 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 - Heat conducted througfi unit area and unit thick face per unit time when temperature difference between opposite faces is unity,is called__________________?
A. thermal resistance
B. thermal coefficient
C. temperature gradient
D. thermal conductivity
E. heat-transfer - 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 - Unit of thermal conductivity in S.I. units is__________________?
A. J/m2 sec
B. J/m °K sec
C. W/m °K
D. A. and C. above
E. B. and C. above - The rate of energy emission from unit surface area through unit solid angle, along a normal to the surface, is known as ________________?
A. emissivity
B. transmissivity
C. reflectivity
D. intensity of radiation
E. absorptivity - 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
