Question

Explain how trapped air helps in insulation. write examples where air has applications as an insulator.

Answer 1

Insulation:

1. Insulation works by limiting heat transport in three different ways: conduction, convection, and radiation (the following figure depicts modes of heat transfer)
2. Heat must transfer from your body to your down jacket via conduction, which occurs when little fibers of feather come into touch with one another.
3. Convection heat transfer occurs through the air, which contains millions of small air holes between the fibers. Each fiber must radiate its heat to another, so, the heat transfer through radiation is also slow.

Explanation:

1. Air is a poor conductor of heat. As air is trapped, particles cannot move around easily.
2. This reduces conduction and convection currents of heat. Hence heat loss is minimal.

Examples of Insulation:

1. Confining the air in definite cells so that it cannot flow is one approach to reduce heat loss through convection. That's why bubble wrap keeps water in cups and glasses warm for longer, and it's the same concept that's used in both warm-weather fabrics and building insulation.
2. Buildings would not keep warm if builders just left wall cavities unfilled because the air in the spaces would be free to transport heat through convection from the inner wall to the outside, causing all of the heat to be rapidly lost.
3. Most methods of building insulation, on the other hand, trap air in cells and restrict convection, allowing them to take advantage of poor heat conductivity of air.
4. Air cavities in cooking utensils.