Which one of the following heat transfers is an example of convection?

Convection is the transfer of heat energy through the actual movement of matter or substances, specifically in fluids like liquids and gases [2]. Boiling water in a pot on a gas stove is a classic example of natural convection; as the water at the bottom is heated, it becomes less dense and rises, while cooler, denser water sinks to take its place, creating a circulatory motion or convection current. In contrast, heating a brass rod involves conduction, where heat moves through a solid without the particles moving from their positions [4]. Feeling warmth from the sun is an example of radiation, which transfers energy via electromagnetic waves and requires no medium [3]. Microwave heating is a volumetric process using electromagnetic radiation to excite molecules, which differs from the fluid-motion-based heat transfer of traditional convection [1].

Sources

1. [1] Science-Class VII . NCERT(Revised ed 2025) > Chapter 7: Heat Transfer in Nature > In a Nutshell > p. 101
2. [2] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 21: Horizontal Distribution of Temperature > Convection > p. 282
3. [4] Science-Class VII . NCERT(Revised ed 2025) > Chapter 7: Heat Transfer in Nature > 7.1 Conduction of Heat > p. 91
4. [3] Science-Class VII . NCERT(Revised ed 2025) > Chapter 7: Heat Transfer in Nature > In a Nutshell > p. 102