Transmission Of Heat Question 201
Question: A metal ball of surface area $ 200\ cm^{2} $ and temperature $ 527^{o}C $ is surrounded by a vessel at $ 27^{o}C $ . If the emissivity of the metal is 0.4, then the rate of loss of heat from the ball is $ (\sigma =5.67\times {{10}^{-8}}J/m^{2}\ -s-k^{4}) $
[MP PMT/PET 1988]
Options:
A) 108 joules approx.
B) 168 joules approx.
C) 182 joules approx.
D) 192 joules approx.
Show Answer
Answer:
Correct Answer: C
Solution:
Rate of heat loss $ E=\sigma ,eA(T^{4}-T _{0}^{4}) $
$ =5.67\times {{10}^{-8}}\times 0.4\times 200\times {{10}^{-4}} $ ´$ [{{(273+527)}^{4}}-{{(273+27)}^{4}}] $
$ =5.67\times {{10}^{-8}}\times 0.4\times 200\times {{10}^{-4}} $ ´$ {{(800)}^{4}}-{{(300)}^{4}} $ =182J/sec
BETA
