Related Questions

In AC.S.R. Conductors, the insulation between aluminium and steel conductors is
A Insulin
B Bitumen
C Varnish
D No insulation is required
Total emissivity of polished silver compared to black body is
A Same
B Higher
C More or less same
D Very much lower
While the total emissivity of a perfect black body is unity, the same for a real body is
A 0
B 1
C > 1
D Between 0 and 1
The rule that resistivity of conductors can be separated into two parts viz. temperature independent and temperature dependent is known as
A Matthiessen’s rule
B Debye rule
C Curie rule
D Onne’s rule
Emissivity of a white polished body in comparison to a black body is
A Higher
B Lower
C Same
D Depends upon the shape of body
The changes in the reflectivity/emissivity with time, is called:
A Spectral variation
B Spatial variation
C Temporal variation
D None of these
Ceramic coating material for furnace refractory, which increases its emissivity and thus the radiation heat transfer rate in the furnace, comprises of
A Graphite powder
B Thoria
C Zircon powder
D Beryllium
A __________ surface has the maximum thermal emissivity out of the following.
A Black & smooth
B Black & rough
C White & smooth
D White & rough
The heat transfer by radiation from a mild steel surface is to be reduced by reducing the emissivity of the surface. This can be best achieved by
A Painting the surface black
B Painting the surface white (with aluminium paint)
C Giving the surface a mirror finish
D Roughening the surface
The emissivity for a black body is
A 0
B 0.5
C 0.75
D 1

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