Question

In which one of the following materials the heat energy propagation is minimum due to conduction heat transfer?

• A. Lead
• B. Copper
• C. Water
• D. Air

Hint:

Materials with lower thermal conductivity transfer heat less effectively. Air has the lowest conductivity among the given materials.

Answer 1

The Correct Option is D

Step 1: Understanding Conductive Heat Transfer.
Fourier's law defines the rate of heat transfer via conduction:\[Q = \frac{kA(T_1 - T_2)}{L}\]Where:
- \( Q \) represents the heat transfer rate,
- \( k \) signifies the material's thermal conductivity,
- \( A \) denotes the heat flow area,
- \( T_1 - T_2 \) indicates the temperature difference,
- \( L \) is the material's thickness.
Step 2: Comparing Material Thermal Conductivities.
- Lead: \( k = 35 \, \text{W/m·K} \), a high thermal conductivity.
- Copper: \( k = 400 \, \text{W/m·K} \), an even higher thermal conductivity.
- Water: \( k = 0.6 \, \text{W/m·K} \), a moderate thermal conductivity.
- Air: \( k = 0.025 \, \text{W/m·K} \), the lowest thermal conductivity.
Step 3: Conclusion
Air's minimal thermal conductivity results in the least heat propagation through conduction. Final Answer: \[ \boxed{\text{Air}} \]