Which of the following is a means of transmitted heat?

• A. Conduction, convection and radiation
• B. Conduction
• C. Convection
• D. Radiation

Answer: (A)

Heat can be transmitted through three distinct mechanisms: conduction, convection, and radiation. Conduction is heat moving through materials by particle interactions, as when a metal spoon gets warm from a hot pot. Convection involves the movement of a fluid (air or liquid), carrying energy with the circulating flow, like warm air rising and circulating in a room. Radiation is heat transferred by electromagnetic waves, which can travel across spaces without touching the objects.

The best answer lists all three modes, because heat transfer in real life can occur by any of these pathways, and often more than one at once. Saying heat is transmitted only by one mechanism—conduction alone, convection alone, or radiation alone—covers just a single route and misses the others that can also occur in buildings.