Heat Transfer:
When two bodies having different temperatures are brought in contact with each other, heat flows from the hotter body to the colder one. Again, when there is a temperature difference between different points of a body, heat flows in the body from the point of higher temperature to the point of lower temperature. The flow of heat from one place to another is called heat transfer.
Types of Heat Transfer:
Heat is transmitted in three different processes:
1. Conduction: It is the process in which heat energy is transmitted from a hotter region to a colder region of a material without any displacement of molecules.
2. Convection: It is the process in which heat is transmitted from a hotter region to a colder region of a material by the actual movement of heated molecules.
3. Radiation: Radiation is the process in which heat is transferred from one place to another in the absence of any material medium or through a material medium present between the two places. The heat from the sun reaches the earth by radiation.