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ISRO Mechanical Engg.: Heat Transfer Quiz 1
Attempt now to get your rank among 1945 students!
Question 1
If thermal conductivity of a material of wall varies as k0(1-
T), the temperature at the center of the wall will be (
is +ve)
T), the temperature at the center of the wall will be (is +ve) Question 2
The spectral emissive power E1 for a diffusely emitting surface is E1 =0 for 
<3
; E1 =150 W/m2
for 3<
< 12
; E1= 300 W/m2
for 12<
<25 
; E1=0 for 
>25
. The total emissive power of the surface over the entire spectrum is
<3; E1 =150 W/m2 for 3<< 12; E1= 300 W/m2 for 12< <25 ; E1=0 for >25. The total emissive power of the surface over the entire spectrum is Question 3
A beaker filled with hot water in a room cools from 70 °C to 65 °C in t1 minutes, 65 °C to 60 in t2 minutes and from 60 °C to 55 °C in t3 minutes. Then,
Question 4
Two insulating materials of thermal conductivity K and 2K are available for lagging a pipe carrying a hot fluid,. If the radial thickness of each material is the same.
Question 5
The Rayleigh number Ra is defined as :
(Where Gr is Grashof Number, Pr is Prandtl Number and Re is Reynold Number)
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