Transmission Of Heat Question 45
A slab consists of two parallel layers of copper and brass of the same thickness and having thermal conductivities in the ratio 1 : 4. If the free face of brass is at $ 35^{o}C $ and that of copper at $ 100^{o}C $ , the temperature of interface is
[IIT 1981; MP PMT 1987, 2001]
Options:
A) 80°C
B) 20°C
C) 60°C
D) 40°C
Show Answer
Answer:
Correct Answer: A
Solution:
Temperature of interface q = $ \frac{K _{1}{\theta _{1}}+K _{2}{\theta _{2}}}{K _{1}+K _{2}} $
$ (\because ,\frac{K _{1}}{K _{2}}=\frac{1}{4}\Rightarrow $ If K1 = K then K2 = 4K)
Therefore $ \theta =\frac{K\times 0+4K\times 100}{5,K} $ = 80°C
BETA
