Transmission Of Heat Question 235
Question: A black body radiates 20 W at temperature $ 227^{o}C $ . If temperature of the black body is changed to $ 727^{o}C $ then its radiating power will be
[CBSE PMT 2002; DCE 1999, 03; AIIMS 2003]
Options:
A) 120W
B) 240 W
C) 320 W
D) 360 W
Show Answer
Answer:
Correct Answer: C
Solution:
For a black body $ \frac{Q}{t}=P=A\sigma T^{4} $
Therefore $ \frac{P _{2}}{P _{1}}={{( \frac{T _{2}}{T _{1}} )}^{4}} $
Therefore $ \frac{P _{2}}{20}={{( \frac{273+727}{273+227} )}^{4}} $
Therefore $ \frac{P _{2}}{20}={{(2)}^{4}} $
Therefore $ P _{2}=320W $
BETA
