Which one of the following heat transfer mechanisms does NOT require a medium?

Heat transfer occurs through three primary mechanisms: conduction, convection, and radiation. Conduction involves the transfer of heat between particles in direct contact without the particles moving from their positions [1][2]. Convection involves the macroscopic movement of fluid particles (liquids or gases) to transport heat [1][3]. Both conduction and convection strictly require a material medium to facilitate the transfer of thermal energy [1][5]. In contrast, radiation is the transfer of energy via electromagnetic waves, such as infrared or visible light [3][4]. Because electromagnetic waves can travel through the vacuum of space, radiation does not require any material medium for its transfer [1][3]. This is evidenced by the Sun's heat reaching the Earth through the vacuum of space [3][5]. Collision is a microscopic process that facilitates conduction but is not considered a separate primary macroscopic heat transfer mechanism [4].

Sources

1. [1] 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
2. [2] Science-Class VII . NCERT(Revised ed 2025) > Chapter 7: Heat Transfer in Nature > In a Nutshell > p. 101
3. [3] Physical Geography by PMF IAS, Manjunath Thamminidi, PMF IAS (1st ed.) > Chapter 21: Horizontal Distribution of Temperature > Radiation > p. 282
4. [5] Science-Class VII . NCERT(Revised ed 2025) > Chapter 7: Heat Transfer in Nature > In a Nutshell > p. 102
5. [4] Science-Class VII . NCERT(Revised ed 2025) > Chapter 7: Heat Transfer in Nature > 7.2.1 Land and Sea Breeze > p. 96