Explain with an activity that air is a bad conductor of heat
The Correct Answer and Explanation is:
Answer:
Activity:
Take two identical metal cups. Fill one with hot water and leave the other empty. Cover both cups tightly with plastic lids. Place a small cube of butter on the lid of each cup, then stick a pin vertically into each butter cube. Now insulate the empty cup by surrounding it with cotton wool or any soft insulating material like a cloth. Observe which pin falls off first as the butter melts.
Explanation
This simple activity shows how air behaves as a poor conductor of heat. In this setup, the cup filled with hot water transfers heat upward through the lid to melt the butter cube. Once the butter melts, the pin falls. The second cup, surrounded by cotton or cloth, contains trapped air pockets, making it better insulated.
Air does not conduct heat efficiently because its molecules are spaced far apart. In solids, atoms are tightly packed, allowing heat to transfer quickly from one particle to another through direct contact. In gases like air, particles are much farther apart. When heat tries to move through air, the energy must travel across these gaps, which takes more time. This reduces the overall heat flow, making air a poor heat conductor.
The cloth or cotton surrounding the second cup traps air. These materials themselves are not good conductors, but their insulating ability largely comes from the air pockets they contain. These trapped air layers slow down the movement of heat. As a result, the butter cube on the second cup melts much more slowly or may not melt at all within the same time.
Many everyday objects take advantage of air’s insulating properties. Double-glazed windows, woolen clothing, and thermos flasks all use layers of trapped air to keep heat from escaping or entering quickly. In this way, air helps maintain temperature but fails to transfer heat efficiently, proving its poor conductivity.
