What is convection?

Convection is defined as the movement of fluids, such as liquids and gases, that facilitates the transfer of heat. This process occurs when warmer parts of a fluid rise due to decreased density, while cooler, denser parts sink. This creates a circulation pattern that helps distribute thermal energy throughout the fluid.

For example, when you heat water in a pot, the water at the bottom heats up first, becomes less dense, and rises to the top, while cooler water moves down to take its place. This continuous cycle allows for efficient heat transfer within the fluid.

The other options refer to different processes that involve energy transfer. The transfer of heat through direct contact describes conduction, where heat moves through materials that are in direct contact without any movement of the material itself. The spread of energy through electromagnetic waves pertains to radiation, where heat energy is transferred through electromagnetic radiation without requiring a medium. The transformation of energy types refers to energy conversion, like turning electrical energy into kinetic energy, which is not directly related to the heat transfer processes described.