Transmission Of Heat Question 86
Question: The ratio of the coefficient of thermal conductivity of two different materials is 5 : 3. If the thermal resistance of the rod of same thickness resistance of the rods of same thickness of these materials is same, then the ratio of the length of these rods will be
[BHU 2000]
Options:
A) 3 : 5
B) 5 : 3
C) 3 : 4
D) 3 : 2
Show Answer
Answer:
Correct Answer: B
Solution:
Thermal resistances are same
Therefore $ \frac{l _{1}}{K _{1}A _{1}}=\frac{l _{2}}{K _{2}A _{2}} $
Therefore $ \frac{l _{1}}{K _{1}}=\frac{l _{2}}{K _{2}} $
$ (\because A _{1}=A _{2}) $
Therefore $ \frac{l _{1}}{l _{2}}=\frac{K _{1}}{K _{2}}=\frac{5}{3} $
BETA
