Properties Of Solids And Liquids Question 440
Question: The rectangular surface of area $ 8 cm\times 4 cm $ of a black body at temperature $ 127{}^\circ C $ emits energy E per second. If the length and breadth are reduced to half of the initial value and the temperature is raised to $ 327{}^\circ C $ , the rate of emission of energy becomes
Options:
A) $ \frac{3}{8}E $
B) $ \frac{81}{16}E $
C) $ \frac{9}{16}E $
D) $ \frac{81}{64}E $
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Answer:
Correct Answer: D
Solution:
[d] $ E=\sigma \times area\times T^{4} $ ;
T increases by a factor $ \frac{3}{2} $ .
Area increases by a factor$ \frac{1}{4} $ .
$ \Rightarrow E’\frac{1}{4}\times {{( \frac{3}{2} )}^{4}}\times E=\frac{81}{64}E $
