Which one of the following is the mode pf heat transfer in which warm material is transported so as to displace a cooler material

Convection is the mode of heat transfer characterized by the actual movement of particles or bulk motion of a fluid (liquid or gas) [c2][c3]. In this process, warmer, less dense material is transported to a different location, effectively displacing cooler, denser material [t5]. Unlike conduction, where heat is transferred through molecular vibrations without the particles changing their positions [c1][c2], convection involves the physical displacement of the medium's molecules [c4]. This transport of internal energy via fluid motion is often referred to as advection within the broader context of convection [t4][t10]. While conduction occurs at the interface between a surface and a fluid, the large-scale transport and mixing that displaces cooler material is strictly the mechanism of convection [t1][t5]. Radiation, by contrast, requires no material medium and transfers energy via electromagnetic waves [c2][t5].

Sources

1. [1] Science-Class VII . NCERT(Revised ed 2025) > Chapter 7: Heat Transfer in Nature > In a Nutshell > p. 101
2. [2] Science-Class VII . NCERT(Revised ed 2025) > Chapter 7: Heat Transfer in Nature > Why is it more comfortable to wear white or light-coloured clothes during summers and dark-coloured clothes during winters? > p. 97
3. [3] Science-Class VII . NCERT(Revised ed 2025) > Chapter 7: Heat Transfer in Nature > In a Nutshell > p. 102
4. [4] Science-Class VII . NCERT(Revised ed 2025) > Chapter 7: Heat Transfer in Nature > Activity 7.3: Let us fi nd out > p. 94
5. [5] https://www.sciencedirect.com/topics/chemical-engineering/heat-convection