Thermal diffusivity of a substance is ____________________?

Related Mcqs:

1. 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

2. 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

3. 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

4. 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

5. 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

6. Thermal conductivity of solid metals with rise in temperature normally___________________?

   A. increases
   B. decreases
   C. remains constant
   D. may increase or decrease depending on temperature
   E. unpredictable

7. 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

8. Which of the following is expected to have highest thermal conductivity_______________?

   A. steam
   B. solid ice
   C. melting ice
   D. water
   E. boiling water

9. Thermal conductivity of a material may be defined as the________________?

   A. quantity of heat flowing in one second through one cm cube of material when opposite faces ^re maintained at a temperature difference of 1°C
   B. quantity of heat flowing in one second through a slab of the material of area one cm square, thickness 1 cm when its faces differ in temperature by 1°C
   C. heat conducted in unit time across unit area through unit thickness when a temperature difference of unity is maintained between opposite faces
   D. all of the above
   E. none of the above

10. 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