Answer:
There are three modes of heat transfer.
1. Conduction
2. Convection
3. Radiation
1. Conduction: Heat transfer through the process of conduction occurs in substances which are in direct contact with each other. It generally takes place in solids.
For example: When frying vegetables in a pan. Heat transfer takes place from flame to the pan and then to the vegetables.
2. Convection: In this process, heat is transferred in the liquid and gases from a region of higher temperature to a region of lower temperature. Convection heat transfer occurs partly due to the actual movement of molecules or due to the mass transfer.
For example: Heating of milk in a pan.
3. Radiation : It is the process in which heat is transferred from one body to another body without involving the molecules of the medium. Radiation heat transfer does not depend on the medium.
For example: In a microwave, the substances are heated directly without any heating medium.