Heat Transfer

41. 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
5. all of the above.

View answer

42. 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
5. all of the above.

View answer

43. 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
5. thermal conductivity.

View answer

44. 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. convert saturated steam into dry steam.

View answer

45. Stefan Boltzmann law is applicable for heat transfer by

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

View answer

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

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

View answer

47. 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. inversely proportional to the thickness of the body
5. all of the above.

View answer

48. The amount of radiation mainly depends on

1. nature of body
2. temperature of body
3. type of surface of body
4. all of the above
5. none of the above.

View answer

49. The concept of overall coefficient of heat transfer is used in case of heat transfer by

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

View answer

50. The concept of overall coefficient of heat transfer is used in heat transfer problems of

1. conduction
2. convection
3. radiation
4. all the three combined
5. conduction and comtection.

View answer