Modes of Heat Transfer — Conduction, Convection and Radiation

Why Heat Transfer Is Everyday Physics

Heat always flows from a hotter body to a colder one, and it can travel in only three ways: conduction, convection and radiation. That single idea explains an enormous range of everyday facts — why cooking pans have wooden or plastic handles, why ice is kept in sawdust, why the freezer compartment sits at the top of a refrigerator, why we wear light-coloured clothes in summer, and why the Sun's heat reaches Earth across empty space.

Exams rarely ask you to define the three modes in isolation. Instead they describe a situation — a boiling pot, a coastal breeze, a thermos flask — and ask which mode is responsible. So the skill that earns marks is recognition: knowing what each mode needs (contact, a moving fluid, or nothing at all) and spotting it quickly inside a real-life example.

1. The heat of the Sun reaches the Earth mainly by which mode?

2. A sea breeze blowing from sea to land during the day is an example of:

3. Which mode of heat transfer can take place in a vacuum?

4. In a thermos (vacuum) flask, the silvered surfaces of the double wall mainly reduce heat loss by:

5. On a cold morning, an iron railing feels colder to touch than a wooden bench kept beside it. Why?

6. Why is the freezer compartment placed at the top of a refrigerator?

7. Which of the following is the best conductor of heat?

8. Light-coloured clothes are preferred in summer because light surfaces: