1. What Is Conduction?
Conduction is the process of heat transfer through a solid without the particles actually moving from one place to another. The heat passes from particle to particle as they vibrate and push against their neighbours.
Conduction is the main mode of heat transfer in solids because their particles are closely packed.
2. How Conduction Works
When one end of a solid is heated, the particles at that end gain energy and vibrate faster. These energetic vibrations are passed along the neighbouring particles, transferring heat through the entire solid.
2.1. Energy Transfer Through Vibrations
In solids, particles cannot move freely. They stay in fixed positions and vibrate. When heated, these vibrations become more energetic and spread through the solid, carrying heat with them.
2.2. Role of Free Electrons in Metals
Metals conduct heat extremely well because they contain free electrons. These electrons move quickly through the metal, carrying energy from the hot region to the cooler region much faster than vibrations alone.
3. Thermal Conductivity
Different materials conduct heat at different rates. This property is measured by thermal conductivity.
Materials with high thermal conductivity are good conductors, while those with low thermal conductivity are poor conductors or insulators.
3.1. Good Conductors
- Silver
- Copper
- Aluminium
- Iron
These materials transfer heat rapidly and are often used in cooking pots, radiators, and electrical appliances.
3.2. Poor Conductors (Insulators)
- Wood
- Plastic
- Glass
- Rubber
- Air
These materials slow down heat transfer and are used for insulation, handles, and protective coverings.
4. Factors Affecting Conduction
The rate of heat transfer through conduction depends on several factors related to the material and the geometry of the object.
4.1. Material of the Object
Metals conduct heat far better than non-metals because of free electrons. Insulators like wood conduct heat slowly because their particles cannot pass energy easily.
4.2. Temperature Difference
A larger temperature difference between the two ends of a solid increases the rate of heat flow.
4.3. Length and Thickness
Heat flows faster through shorter lengths and thinner pieces. Long rods take more time to transfer heat from one end to the other.
4.4. Cross-Sectional Area
A thicker rod with a larger cross-sectional area allows more heat to pass through at the same time.
5. Conduction in Daily Life
Conduction plays a major role in everyday situations, often without us noticing it. Many familiar experiences can be explained through conduction.
5.1. Metal Spoon Getting Hot
When the tip of a metal spoon is placed in hot tea, heat travels quickly up the spoon to the handle because metals are good conductors.
5.2. Insulated Handles
Pots and pans have wooden or plastic handles because these materials are poor conductors and prevent hands from getting burned.
5.3. Cooking Utensils
Cookware with copper or aluminium bottoms heats up quickly and spreads heat evenly due to good conduction.
5.4. Warm Floors
In winter, floors feel cold because they conduct heat from your feet. Carpets feel warmer because they act as insulators.
6. Applications of Conduction
Understanding conduction helps in designing and selecting materials for heating, insulation, and temperature control.
6.1. Heat Sinks in Electronics
Heat sinks are made of aluminium or copper to quickly conduct heat away from electronic components.
6.2. Thermal Insulation
Homes use insulating materials like fiberglass to reduce heat loss in winter and heat gain in summer.
6.3. Building Design
Glass windows, thick walls, and flooring materials are chosen based on how much heat they conduct.