A black body absorbs all radiations. As a result of absorption of these radiations
A.A black body shines
B.The temperature of black body rises
C.Black body radiates energy to other bodies
D.Black body becomes good conductor of heat
Category: Heat Transfer Mcqs
When metallic surfaces are oxidized the emissivity
A.Increases
B.Decreases
C.Does not change
D.Depends on the temperature
E.Depends on other factors
The unit of thermal conductivity in S.I. units is
A.W/m-hr-?K
B.W/m-hr?C
C.W/m?K
D.KJ/m-hr?C
E.KJ/m-hr-?K
A Foreman of an automobile workshop wants to measure the temperature inside the piston of a car, whose temperature will be of the order of 700?C (accurate upto 1?C). The best thermometer to use is
A.Platinum resistance thermometer
B.Thermo electric thermometer
C.Constant volume hydrogen thermometer
D.Constant volume nitrogen thermometer
E.Optical pyrometer
Which method can be used for heating wood?
A.Flame heating
B.Resistance heating
C.Dielectric heating
D.Radiation heating
E.Any of the above
Which of the following is wrong:
A.Rough surfaces are better radiators than smooth surfaces
B.Highly polished mirror like surfaces are very good radiators
C.Black surfaces are better absorbers than white ones
D.Black surfaces are better radiators than white ones
Which dimensionless number correlates the relative thickness of the hydrodynamic and thermal boundary layers?
A.Prandlt number
B.Nusselt number
C.Crash off number
D.Mach number
A relationship between the temperature of a black body and the wavelength at which the maximum value of monochromatic emission power occurs, is established under
A.D’ lambert’s rule
B.Wein’s displacement law
C.Stefan-Bolzmann’s law
D.Kirchhoff’s law
E.Planck’s law
The expression (A2-A1)/loge (A2/A1) for a hollow cylinder is known as
A.Logarithmic mean radius
B.Mean area of heat transfer
C.The rate of heat transfer
D.None of the above
