Question

The correct sequence of following materials with increased thermal conductivity is ------

• A. Wood - Aluminium - Brass - Steel
• B. Wood - Steel - Brass - Aluminium
• C. Steel - Brass - Aluminium - Wood
• D. Wood - Brass - Aluminium - Steel

Hint:

Pure metals (like Aluminium and Copper) always have higher thermal conductivities than their alloys (like Brass and Steel), which in turn are much more conductive than non-metals (like Wood).

Answer 1

The Correct Option is B

Step 1: Understanding the Concept:
Different classes of materials (such as organic polymers, alloys, and pure metals) have distinct thermal conductivities based on their density and electronic structures.

Step 2: Detailed Explanation:
Let us compare the thermal conductivities (\(k\)) of the materials listed:
1. Wood: An organic, porous material with very low thermal conductivity (\(k \approx 0.1\text{--}0.2\ \text{W/m}\cdot\text{K}\)). It acts as an insulator.
2. Steel (Carbon steel): An iron alloy with moderate thermal conductivity (\(k \approx 45\text{--}50\ \text{W/m}\cdot\text{K}\)).
3. Brass: A copper-zinc alloy with higher thermal conductivity (\(k \approx 110\ \text{W/m}\cdot\text{K}\)).
4. Aluminium: A pure, highly conductive metal with very high thermal conductivity (\(k \approx 205\ \text{W/m}\cdot\text{K}\)).
Arranging these in order of increasing thermal conductivity:
Wood \(<\) Steel \(<\) Brass \(<\) Aluminium.

Step 3: Final Answer:
The correct sequence of increasing thermal conductivity is Wood - Steel - Brass - Aluminium.