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Two rods of same material, same cross-section, but lengths L and 2L are joined in series — JEE Physics

RBRitika Bose · 12 Asked 1mo ago 1,370 views 1 answer

Two rods of same material, same cross-section, but lengths $L$ and $2L$ are joined in series. The ends are at temperatures 100°C and 0°C. Find the temperature at the junction.

1 Answer

RRiteshBasnet93 ✓ Accepted · 1mo ago ▲ 32

In steady state, heat flow rate is equal:

$$\frac{KA(100-T)}{L} = \frac{KA(T-0)}{2L}$$

$$2(100-T) = T \Rightarrow 200 - 2T = T \Rightarrow T = 66.7°C$$

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Discussion (4)

TS
Why do we take the positive value only in the last step?
Tushar Saxena · 1mo ago
T
Tip for others: you can verify the answer quickly by checking the units.
TharushiFernando19 · 1mo ago
PI
Is there a faster shortcut for this in the actual exam? Time is tight.
Pooja Iyer · 1mo ago
IM
Is there a faster shortcut for this in the actual exam? Time is tight.
Isha Malhotra · 30d ago
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