Transmission Of Heat Question 25
In which case does thermal conductivity increase from left to right
[NCERT 1974, 76; AFMC 2000]
Options:
A) Al, Cu, Ag
B) Ag, Cu, Al
C) Cu, Ag, Al
D) Al, Ag, Cu
Show Answer
Answer:
Correct Answer: A
Solution:
$ \frac{K _{1}A({\theta _{1}}-\theta )}{l _{1}}=\frac{K _{2}A(\theta -{\theta _{2}})}{l _{2}} $ is better conductor than $ K _{1}=K _{2} $ and
$ \Rightarrow K _{1}A({\theta _{1}}-\theta )=K _{2}A(\theta -{\theta _{2}}) $ is a better conductor than
$ \Rightarrow \theta =\frac{K _{1}{\theta _{1}}+K {2}{\theta {2}}}{K {1}+K {2}} $ . Hence conductivity in increasing order is $ K=\frac{2K {1}K {2}}{K {1}+K {2}}=\frac{2K{1}K{2}}{K{1}+K{2}}=\frac{2K{1}K{2}}{K{1}+K{2}} $ .
BETA
