Heat Transfer MCQs Quiz Multiple Choice Questions & Answers

1. Thermal diffusivity is

1. a dimensionless parameter
2. function of temperature
3. used as mathematical model
4. a physical property of the material

2. Which of the following has maximum value of thermal conductivity

1. aluminium
2. steel
3. brass
4. copper

3. Which of the following is the case of heat transfer by radiation

1. blast furnace
2. heating of building
3. cooling of parts in furnace
4. heat received by a person from fireplace

4. Sensible heat is the heat required to

1. change vapour into liquid
2. change liquid into vapour
3. increase the temperature of a liquid of vapour
4. convert water into steam and superheat it

5. Total heat is the heat required to

1. change vapour into liquid
2. change liquid into vapour
3. increase the temperature of a liquid or vapour
4. convert water into steam and superheat it

6. Thermal conductivity of glass-wool varies from sample to sample because of variation in

1. composition
2. density
3. porosity
4. all of the above.

7. When heat is transferred from one particle of hot body to another by actual motion of the heated particles, it is referred to as heat transfer by

1. conduction
2. convection
3. radiation
4. conduction and convection

8. When heat is transferred form hot body to cold body, in a straight line, without affecting the intervening medium, it is referred as heat transfer by

1. conduction
2. convection
3. radiation
4. conduction and convection

9. When heat is Transferred by molecular collision, it is referred to as heat transfer by

1. conduction
2. convection
3. radiation
4. scattering

10. Heat transfer in liquid and gases takes place by

1. conduction
2. convection
3. radiation
4. conduction and convection

11. Heat flows from one body to other when they have

1. different heat contents
2. different specific heat
3. different atomic structure
4. different temperatures

12. The amount of heat flow through a body by conduction is

1. directly proportional to the surface area of the body
2. directly proportional to the temperature difference on the two faces of the body
3. dependent upon the material of the body
4. all of the above.

13. Thermal diffusivity of a substance is

1. directly proportional to thermal con¬ductivity
2. inversely proportional to density of substance
3. inversely proportional to specific heat
4. all of the above

14. Heat is transferred by all three modes of transfer, viz, conduction, convection and radiation in

1. electric heater
2. steam condenser
3. melting of ice
4. boiler.

15. Pick up the wrong case. Heat flowing from one side to other depends directly on

1. face area
2. time
3. thickness
4. temperature difference

16. Cork is a good insulator because it has

1. free electrons
2. atoms colliding frequency
3. low density
4. porous body

17. Which of the following has least value of conductivity

1. glass
2. water
3. plastic
4. air.

18. Moisture would find its way into insulation by vapour pressure unless it is prevented by

1. high thickness of insulation
2. high vapour pressure
3. less thermal conductivity insulator
4. a vapour seal

19. Which of the following is a case of steady state heat transfer

1. I.C. engine
2. air preheaters
3. heating of building in winter
4. none of the above.

20. The insulation ability of an insulator with the presence of moisture would

1. increase
2. decrease
3. remain unaffected
4. may increase/decrease depending on temperature and thickness of insulation

21. Thermal conductivity of solid metals with rise in temperature normally

1. increases
2. decreases
3. remains constant
4. may increase or decrease depending on temperature

22. Thermal conductivity of non-metallic amorphous solids with decrease in temperature

1. increases
2. decreases
3. remains constant
4. may increase or decrease depending on temperature

23. Thermal conductivity of water in general with rise in temperature

1. increases
2. decreases
3. remains constant
4. may increase or decrease depending on temperature

24. Thermal conductivity of air with rise in temperature

1. increases
2. decreases
3. remains constant
4. may increase or decrease depending on temperature

25. Heat transfer by radiation mainly depends upon

1. its temperature
2. nature of the body
3. kind and extent of its surface
4. all of the above

26. The thermal diffusivities for solids are generally

1. less than those for gases
2. jess than those for liquids
3. more than those for liquids and gases
4. more or less same as for liquids and gases

27. Heat is closely related with

1. liquids
2. energy
3. temperature
4. entropy

28. Thermal diffusivity of a substance is .

1. proportional of thermal conductivity
2. inversely proportional to k
3. proportional to (k)
4. inversely proportional to k2

29. All radiations in a black body are

1. reflected
2. refracted
3. transmitted
4. absorbed

30. Which of the following is expected to have highest thermal conductivity

1. steam
2. solid ice
3. melting ice
4. water

31. Metals are good conductors of heat because

1. their atoms collide frequently
2. their atoms-are relatively far apart
3. they contain free electrons
4. they have high density

32. Which of the following property of air does not increase with rise in temperature

1. thermal conductivity
2. thermal diffusivity
3. density
4. dynamic viscosity

33. Temperature of steam at around 540°C can be measured by

1. thermometer
2. radiatiouv pyrometer
3. thermistor
4. thermocouple

34. Heat transfer takes place as per

1. zeroth law of thermodynamics
2. first law of thermodynamic
3. second law of the thermodynamics
4. Kirchoffs law