Heat Transfer MCQ Quiz - Multiple Choice Questions & Answers Page 2

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