Heat can be transferred from one body to another through three main mechanisms: conduction, convection, and radiation.
Conduction: Conduction is the process of heat transfer through direct contact between two objects or substances. When two objects at different temperatures come into contact, the hotter object transfers heat energy to the cooler object. The heat is transferred from the higher energy particles to the lower energy particles, causing them to gain kinetic energy and increase in temperature. Metals are good conductors of heat due to the mobility of their electrons, while non-metals are generally poorer conductors.
Convection: Convection involves the transfer of heat through the movement of fluids, such as liquids or gases. When a fluid is heated, its particles gain energy, become less dense, and rise. As a result, the cooler, denser fluid around it moves in to take its place and gets heated in turn. This creates a continuous circulation of fluid, transferring heat from one region to another. Convection is commonly observed in processes like boiling water or the movement of air currents.
Radiation: Radiation is the transfer of heat through electromagnetic waves, without the need for a medium or direct contact between objects. All objects with a temperature above absolute zero emit thermal radiation in the form of electromagnetic waves. These waves carry energy and can travel through vacuum or transparent mediums. When radiation encounters an object, it can be absorbed, reflected, or transmitted. A classic example of radiation is the heat we receive from the Sun.
In many real-world situations, heat transfer occurs through a combination of these mechanisms. Understanding how heat is transferred is important in various fields, including engineering, thermodynamics, and climate science.