Heat Transfer by Conduction Experiment for Schools, Teachers, and Students
Conduction is the process of heat transfer through a solid or between two solids in direct contact without any movement of matter. The transfer of heat occurs due to the vibration of particles and collisions between neighboring molecules.
Theory
- In solids, particles are tightly packed, and they cannot move freely. When one part of the solid is heated, its particles gain energy and vibrate more vigorously.
- These particles transfer energy to neighboring particles through collisions, passing the heat along the material.
- The rate of heat transfer depends on the temperature gradient, the material’s thermal conductivity, and the surface area of the material.
Mathematical Expression of Heat Transfer (Fourier’s Law)
The rate of heat transfer by conduction is given by:
Q = (kA(T₁ – T₂)t) / d
Where:
- Q: Heat transferred (J)
- k: Thermal conductivity of the material (W/m·K)
- A: Cross-sectional area of the material (m²)
- T₁, T₂: Temperatures of the two ends (K)
- t: Time of heat transfer (s)
- d: Thickness of the material (m)
Key Points
- Conduction occurs primarily in solids.
- Heat flows from regions of higher temperature to regions of lower temperature.
- Materials with higher thermal conductivity (k) conduct heat more effectively.
Examples of Heat Transfer by Conduction
- A metal rod gets heated when one end is placed in a flame.
- Heat transfer through the walls of a cooking utensil while cooking food.
- The handle of a spoon becomes hot when its other end is in a hot liquid.
- Walking barefoot on hot sand or concrete, where heat conducts to the feet.
Thermal Conductivity
The thermal conductivity (k) of a material determines how easily heat can pass through it.
- Materials with high thermal conductivity, like metals (e.g., copper, aluminum), are good conductors of heat.
- Materials with low thermal conductivity, like wood, rubber, and glass, are poor conductors and are called insulators.
Applications of Heat Conduction
- Cooking Utensils: Metals with high thermal conductivity are used for faster heat transfer.
- Insulation in Homes: Materials with low thermal conductivity, like fiberglass and foam, are used to reduce heat loss.
- Heat Sinks in Electronics: Metals like aluminum are used to dissipate heat from electronic devices.
- Thermal Blankets: Used to trap body heat and minimize heat conduction in cold environments.
Observations
- Heat transfer by conduction occurs without the movement of matter.
- The rate of conduction increases with a higher temperature difference (T₁ – T₂).
- Good conductors of heat (like metals) transfer heat faster than insulators (like wood or plastic).
- Thicker materials or smaller surface areas reduce the rate of heat transfer.
