Category: Heat Transfer

A. change vapour into liquid
B. change liquid into vapour
C. increase the temperature of a liquid of vapour
D. convert water into steam and superheat it
E. convert saturated steam into dry steam

A. directly proportional to the surface area of the body
B. directly proportional to the temperature difference on the two faces of the body
C. dependent upon the material of the body
D. inversely proportional to the thickness of the body
E. all of the above

A. zeroth law of thermodynamics
B. first law of thermodynamic
C. second law of the thermodynamics
D. Kirchoff’s law E. Stefan’s law

A. radiant heat is proportional to fourth power of absolute temperature
B. emissive power depends on temperature
C. emissive power and absorptivity are constant for all bodies
D. ratio of emissive power to absorptive power is maximum for perfectly black body
E. ratio of emissive power to absorptive power for all bodies is same and is equal to the emissive power of a perfectly black body

A. electric heater
B. steam condenser
C. melting of ice
D. refrigerator condenser coils
E. boiler

A. it is impossible to transfer heat from low temperature source to t high temperature source
B. heat transfer by radiation requires no medium
C. all bodies above absolute zero emit radiation
D. heat transfer in most of the cases takes place by combination of conduction, convection and radiation
E. rate of heat transfer depends on thermal conductivity and temperature difference

A. 0.45
B. 0.55
C. 0.40
D. 0.75
E. 0.60

A. absolute temperature
B. square of temperature
C. fourth power of absolute temperature
D. fourth power of temperature
E. cube of absolute temperature

A. liquids
B. energy
C. temperature
D. entropy
E. enthalpy

A. Grashoff no. and Reynold no
B. Grashoff no and Prandtl no.
C. Prandtl no. and Reynold no
D. Grashoff no., Prandtl no and Reynold no
E. none of the above