Practical No. 13: Determination of Coefficient of thermal conductivity.

 Practical No. 13: Determination of Coefficient of thermal conductivity.

• The value of coefficient of thermal conductivity (K) for the material of the rod indicates the ability of the material to conduct heat. Comparing it to standard values can help identify the material (e.g., copper, aluminum).

• It is concluded that Searle’s apparatus provides an effective method for determining the thermal conductivity of good conductors.
• It is recommended to ensure a steady state is achieved (constant θ₁, θ₂, θ₃, θ₄) before collecting water to get accurate results.

• Answer: The copper rod is covered with insulating material to prevent heat loss to the surroundings through radiation and convection. This ensures that all the heat passing through section AB is carried away by the water flowing in the spiral tube, making the calculations accurate.

• Answer: (c) Does not change with time and it remain same at all points of the body.
  • Clarification: In a steady state, the temperature at each specific point does not change with time. However, there is a temperature gradient across the body (temperature is different at different points, like θ₁ and θ₂).

• Answer: This indicates that a steady state has been achieved. The rate at which heat is entering any section of the rod is equal to the rate at which it is leaving that section. Therefore, the temperature at any fixed point does not change with time.

• Answer: The rate of heat conduction (Q/t) is directly proportional to the area of cross-section (A). Therefore, if the area is doubled, the amount of heat conducted per second will also double.

• Answer: No, this method is not suitable for bad conductors.
  • Reason: Bad conductors have very low thermal conductivity. It would be very difficult to achieve a steady state and a measurable temperature gradient across a practical length of a bad conductor using this setup. Methods like Lee’s Disc are used for bad conductors.