Heat is transferred by the movement of air, matter, or liquid around a body. Which mode is this?

Heat is transferred by the movement of air, matter, or liquid around a body. Which mode is this?

• A. Conduction
• B. Convection
• C. Radiation
• D. Evaporation

Answer: (B)

Convection is heat transfer by the motion of a fluid around a body. When a hot object heats nearby air, the air becomes less dense and rises, while cooler air moves in to replace it, creating convection currents. This movement of air or liquid carries thermal energy with it, so heat is transferred as the fluid circulates. This is different from conduction, which needs direct contact for energy to transfer through a substance, and from radiation, which transfers energy via electromagnetic waves without relying on moving matter. Evaporation involves a phase change at a surface and is a cooling process, not the general mechanism of heat transfer by fluid movement.

Convection is heat transfer by the motion of a fluid around a body. When a hot object heats nearby air, the air becomes less dense and rises, while cooler air moves in to replace it, creating convection currents. This movement of air or liquid carries thermal energy with it, so heat is transferred as the fluid circulates. This is different from conduction, which needs direct contact for energy to transfer through a substance, and from radiation, which transfers energy via electromagnetic waves without relying on moving matter. Evaporation involves a phase change at a surface and is a cooling process, not the general mechanism of heat transfer by fluid movement.