Transfer of heat by the movement of air or liquid is known as _______

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

Answer: (D)

This question tests how heat moves with fluids. When heat is carried by the actual movement of air or water, the process is convection. Hot fluid becomes buoyant and rises, cooler fluid moves in to replace it, and this circulating flow transfers heat through the space or medium.

Conduction is heat transfer through direct contact at the molecular level and can occur in solids or stationary fluids. Radiation is heat transfer by electromagnetic waves and does not require a medium. Advection is the transport of substances by the bulk motion of a fluid and is a related idea, but in the context of heat transfer, convection is the term used to describe heat movement with moving air or liquid.