What type of energy transfer process is primarily involved in thermal expansion?

Thermal expansion primarily involves the process of convection. When a substance is heated, its particles gain kinetic energy and begin to move more rapidly. This increase in motion causes the particles to spread apart, resulting in an expansion of the material. In fluids, such as gases and liquids, this thermal expansion leads to changes in density and causes the warmer, less dense areas to rise, while cooler, denser areas sink. This movement creates a circulation pattern, thereby transferring heat through convection currents.

While conduction and radiation are also methods of heat transfer, they are not the primary mechanisms responsible for the expansion behavior. Conduction involves direct contact and the transfer of thermal energy through a material without the movement of the material itself. Radiation involves the transfer of energy through electromagnetic waves, which does not directly contribute to the physical expansion of materials due to temperature increases. Therefore, convection most accurately describes the energy transfer process relevant to thermal expansion.