Transmission Of Heat Question 335
Question: Three conducting rods of same material and cross-section are shown in figure. Temperatures of A, D and C are maintained at $ 20{}^\circ C,90{}^\circ C $ and $ 0{}^\circ C $ . The ratio of lengths of BD and BC if there is no heat flow in AB is:
Options:
A) 2/7
B) 7/2
C) 9/2
D) 2/9
Show Answer
Answer:
Correct Answer: B
Solution:
[b] There is no heat flow through AB. Hence $ {\theta _{B}}=20^{o}C,H _{DB}=H _{BC} $
$ \
Therefore $ $ \frac{(90-20)}{l _{BD}/KA}=\frac{(20-0)}{l _{BC}/KA} $
$ \
Therefore $ $ \frac{l _{BD}}{l _{BC}}=\frac{7}{2} $
BETA
