Transmission Of Heat Question 250
Question: A black body of surface area 10cm2 is heated to 127°C and is suspended in a room at temperature 27°C. The initial rate of loss of heat from the body at the room temperature will be
[Pb. PET 1997]
Options:
A) 2.99 W
B) 1.89 W
C) 1.18 W
D) 0.99 W
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Answer:
Correct Answer: D
Solution:
Loss of heat $ \Delta Q=A\varepsilon \sigma (T^{4}-T _{0}^{4})t $
Therefore Rate of loss of heat $ \frac{\Delta Q}{t}=A\varepsilon \sigma (T^{4}-T _{0}^{4}) $
$ =10\times {{10}^{-4}}\times 1\times 5.67\times {{10}^{-8}}{{{273+127)}^{4}}-{{(273+27)}^{4}}} $ = 0.99 W.
BETA
