Thermal Properties of Matter - Result Question 20
20. Two metal rods 1 and 2 of same lengths have same temperature difference between their ends. Their thermal conductivities are $K_1$ and $K_2$ and cross sectional areas $A_1$ and $A_2$, respectively. If the rate of heat conduction in $rod 1$ is four times that in rod 2, then
[NEET Kar. 2013]
(a) $K_1 A_1=K_2 A_2$
(b) $K_1 A_1=4 K_2 A_2$
(c) $K_1 A_1=2 K_2 A_2$
(d) $4 K_1 A_1=K_2 A_2$
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Answer:
Correct Answer: 20. (b)
Solution:
(b) $Q_1=4 Q_2$ (Given)
$\Rightarrow \frac{K_1 A_1 \Delta t}{L}=4 \frac{K_2 A_2 \Delta t}{L} \Rightarrow K_1 A_1=4 K_2 A_2$.
