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.Management Sciences
Category: Heat Transfer
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
The ratio of the emissive power and absorptive power of all bodies is the same and is equal to the emissive power of a perfectly black body. This statement is known as_________________?
A. Krichoff’s law
B. Stefan’s law
C. Wien’ law
D. Planck’s law
E. Black body law
A grey body is one whose absorptivity_________________?
A. varies with temperature
B. varies with wavelength of the incident ray
C. is equal to its emissivity
D. does not vary with temperature and. wavelength of the incident ray
E. none of the above
Which of the following is expected to have highest thermal conductivity_______________?
A. steam
B. solid ice
C. melting ice
D. water
E. boiling water
A steam pipe is to be insulated by two insulating materials put over each other . For best results__________________?
A. better insulation should be put over pipe and better one over it
B. inferior insulation should be put over pipe and better one over it
C. both may be put in any order
D. whether to put inferior OIL over pipe or the better one would depend on steam temperature
E. unpredictable
Thermal diffusivity of a substance is ____________________?
A. proportional of thermal conductivity
B. inversely proportional to k
C. proportional to (k)
D. inversely proportional to k2
E. none of the above
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