For all substances the absorptivity must lie between
A.0 and 0.1
B.?1 and +1
C.?0.5 and + 0.5
D.0 and 1
E.0 and + 0.5
Category: Heat Transfer Mcqs
The sensible heat of hot industrial gases can be recovered by a
A.Regenerator
B.Recuperator
C.Either of (A) and (B) above
D.None of the above
Two pieces of wood are placed in sunlight. One is painted white and the other is painted black. It can be concluded that
A.White painted wood will not absorb any solar radiation
B.Black painted wood will not absorb any solar radiation
C.Black painted wood will absorb less heat as compared to white painted wood
D.Black painted wood will absorb more hcat as compared to white painted wood
There are two spheres of copper the ratio of their radii being 1 : 3 both at the same temperature. The ration of heat contents will be
A.1 ; 1
B.1 ; 3
C.1 ; 9
D.1 ; 27
E.1 ; 81
An isotherm is a graph
A.Connecting points of equal temperature
B.Showing pressure volume changes at constant temperature
C.Connecting points of equal pressure
D.Showing product of pressure and volume against pressure
E.Constant temperature
When a body is in thermal equilibrium with its surroundings, the absorptivity and the emissivity of the body are same. This Law is known as
A.Wein’s Law
B.Kirchhoff’s law
C.Stefan Boltzmann’s law
D.None of the above
Radiation heats transfer between two surfaces can be reduced by
A.Polishing the surface
B.Bringing the surfaces closer together
C.Preheating the surfaces closer together
D.Introducing radiation shield between the surfaces
Thermal conductivity of water at 20?C is nearly
A.0.051
B.0.09
C.0.11
D.0.5
E.1
Which dimensionless number can be used for convective heat transfer?
A.Graetz number
B.Nusselt number
C.Mach number
D.Froude number
