AP EAMCET · PHYSICS · Thermal Properties of Matter

Three rods of same dimensional have thermal conductivity \(3 K, 2 K\) and \(K\). They are arranged as shown in the figure below

Then, the temperature of the junction in steady state is

A \(\frac{200}{3}^{\circ} \mathrm{C}\)
B \(\frac{100}{3}{ }^{\circ} \mathrm{C}\)
C \(75^{\circ} \mathrm{C}\)
D \(\frac{50}{3}{ }^{\circ} \mathrm{C}\)

Verified Solution

Answer & Solution

Correct Answer

(B) \(\frac{100}{3}{ }^{\circ} \mathrm{C}\)

Step-by-step Solution

Detailed explanation

According to the figure \(\begin{array}{rlrl} H & =H_1+H_2 \\ \Rightarrow & \frac{3 K A(100-T)}{l} & =\frac{2 K A(T-50)}{l}+\frac{K A(T-0)}{l} \\ \\ 300-3 T =2 T-100+T \\ 6 T =400 \\ \text { or } T =\frac{200}{3}{ }^{\circ} \mathrm{C} \end{array}\)

Apply the relevant identity from the chapter and substitute the values established in the previous step, keeping the original constraint in view.

Use the simplified expression to isolate the unknown, then plug the result back into the question setup to confirm the working is internally consistent.

Cross-check against a boundary or limiting case. Both the dimensional balance and the qualitative behaviour at the extreme should agree with the candidate answer.

Combine the steps above to identify the correct option. The remaining choices each fail at least one of the consistency, dimensional, or boundary checks.

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Three rods of same dimensional have thermal conductivity \(3 K, 2 K\) and \(K\). They are arranged as shown in the figure belowThen, the temperature of the junction in steady state is

Step-by-step Solution

Three rods of same dimensional have thermal conductivity \(3 K, 2 K\) and \(K\). They are arranged as shown in the figure below

Then, the temperature of the junction in steady state is