Question

Explain three modes of heat transfer with applications

Answer 1

The three basic modes of heat transfer are as follows -

1)conduction

2)convection

3)radiation

Conduction of heat: Heat conduction is a process in which heat is transferred from the hotter part to the colder part in a body without involving any actual movement of the molecules of the body. Heat transfer takes place from one molecule to another molecule as a result of the vibratory motion of the molecules. 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.

Based on the conductivity of heat, substances can be classified as conductors and insulators. Substances which conduct heat easily are known as conductors and those that do not conduct heat are known as insulators.

Convection of heat: 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.

Radiation of heat: It is the process in which heat is transferred from one body to another body without involving the molecules or 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.

Answer 2

Answer

Heat is transfered via solid material (conduction), liquids and gases (convection), and electromagnetical waves (radiation). Heat is usually transfered in a combination of these three types and seldomly occurs on its own.