கோடை வெப்பத்தை தணிக்க RAJU BHAI -யின் திட்டம் | Thermal Conductivity
2 Hours 5 Minutes
Thermal conductivity and insulation for students: learn how heat travels through roof materials and how insulators block it. A Tamil science lesson.
- Thermal imaging of clay tile, concrete, and asbestos roofs
- How air molecules transfer heat across a room through convection
- How thermocol, woven palm leaves, and cooling tiles trap air
What this lesson teaches
Thermal conductivity is the ability of a material to conduct and transfer heat through itself. Materials with high thermal conductivity allow heat to pass through quickly, while thermal insulators conduct heat very slowly and help block heat.
Thermal conductivity in roof materials
When observed with a thermal imaging camera, an asbestos sheet roof lets in more heat than a concrete roof or a clay tile roof. Asbestos allows heat to pass through rapidly because it has high thermal conductivity. Materials that conduct heat slowly protect the space beneath them from heating up too fast. In daily life, a metal cup made of copper heats up quickly when hot coffee is poured into it, while a glass tumbler warms up much more slowly because glass has lower thermal conductivity.
How heat spreads by convection
Roof heat spreads through an enclosed room by a process called convection. Heat from the hot roof warms the air molecules touching it. As air moves inside the room, these warmed air molecules carry heat and transfer it to other air molecules, gradually warming the entire space. The same process of convection occurs when water is heated in a vessel and circulating liquid molecules spread the heat.
How thermal insulators work
Materials that resist heat flow are called thermal insulators, and most work by trapping air. Thermocol is composed of more than ninety percent air pockets that lock air molecules in place so they cannot move freely to transfer heat. Woven coconut and palm leaves (olai) used in traditional thatched roofs work the same way by trapping pockets of still air between their fibers. Without freely moving air molecules, convection cannot take place, and heat is prevented from entering the room.
Modern cooling techniques
- Terracotta cooling tiles placed on concrete rooftops contain hollow openings that trap stationary air.
- False ceilings installed below a concrete slab create an insulating air space that limits heat transfer into the room.
- Lightweight concrete incorporates tiny air pockets to reduce structural weight while acting as an insulator against heat.