Question

Two rods of same length and transfer a given amount of heat 12 Second, when they are joined as shown in figure (i) But When they tire joined as shown in figure (ii), then they will transfer same heat in same. conditions in

• A. 24 s
• B. 13 s
• C. 15 s
• D. 48 s

Answer 1

Answer: (D)

48 s

We know that heat flow is given as: $Q=\frac{KA\Delta T}{L}$
If they are connected parallel to each other, $t\propto \frac{L}{A}$
Now, if they are connected in series then: $t^{{}^{\prime }}\propto \frac{2L}{\frac{A}{2}}$
So, $t^{{}^{\prime }}=4\times t=4\times 12=48second$