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.Management Sciences
Category: Heat Transfer
Heat flows from one body to other when they have_________________?
A. different heat contents
B. different specific heat
C. different atomic structure
D. different temperatures
E. none of the above
A grey body is one whose absorptivity _________________?
A. varies with temperature
B. varies with the wave length of incident ray
C. varies with both
D. does not vary with temperature and wave length of the incident ray
E. there is no such criterion
Total heat is the heat required to__________________?
A. change vapour into liquid
B. change liquid into vapour
C. increase the temperature of a liquid or vapour
D. convert water into steam and superheat it
E. convert saturated steam into dry steam
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
Depending on the radiating properties, a body will be black when_________________?
A. p = 0, x = 0 and a = 1
B. p= l,T = 0anda = 0
C. p = 0, x = 1 and a = 0
D. x = 0, a + p = 0
E. a = 0,x + p= 1.
where a = absorptivity, p == reflectivity, X = transmissivity
Depending on the radiating properties, body will be transparent when________________?
A. p = 0, x = 0 and a = 1
B. p=l,x = 0,anda = 0
C. p = 0, T= l,anda = 0
D. X = 0, a + p = 1
E. a = 0,x + p= 1
The ratio of the energy absorbed by the body to total energy falling on it is called_________________?
A. absorptive power
B. emissive power
C. absorptivity
D. emissivity
E. none of the above
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
When heat is Transferred by molecular collision, it is referred to as heat transfer by __________________?
A. conduction
B. convection
C. radiation
D. scattering
E. convection and radiation
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
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