What is the term for fluid motion between regions of unequal heating?

What is the term for fluid motion between regions of unequal heating?

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

Answer: (A)

Convection is the transfer of heat by the movement of the fluid itself. When part of a fluid is heated, it becomes less dense and rises, while cooler, denser fluid sinks, creating a circulating flow that moves energy from the hotter region to the cooler region. This bulk motion of the fluid is what carries heat in liquids and gases. Conduction is heat transfer through direct contact without bulk fluid motion, radiation is heat transfer by electromagnetic waves (even through space), and evaporation is a phase-change process at a surface, not the general fluid motion between heated and cooled regions. So the fluid motion between regions of unequal heating is convection.

Convection is the transfer of heat by the movement of the fluid itself. When part of a fluid is heated, it becomes less dense and rises, while cooler, denser fluid sinks, creating a circulating flow that moves energy from the hotter region to the cooler region. This bulk motion of the fluid is what carries heat in liquids and gases. Conduction is heat transfer through direct contact without bulk fluid motion, radiation is heat transfer by electromagnetic waves (even through space), and evaporation is a phase-change process at a surface, not the general fluid motion between heated and cooled regions. So the fluid motion between regions of unequal heating is convection.