Question

What are the three types of heat transfer and what are some examples and application of each type? Which type do you encounter the most in your everyday life?

Answer 1

There are three types of heat transfer that can occur in any process.

1. Conduction
2. Convection
3. Radiation

• Conduction:- The phenomena of conduction occurs at molecular level. Whenever the medium between two end is stationary conduction occurs which we can normally see in solids. In liquids also conduction takes place first before convection.Molecules at higher temperature have high kinetic energy so they vibrate and collid with the adjacent molecules which are at lower temperature and thus transfers the heat. This is known as the diffusion of energy. It is not necessary that conduction only occurs in solids.

• Convection:- Whenever the medium between two points has a relative motion then it is convection. Convection is a surface phenomenon. While heating, density difference occurs of the atoms or molecules at the part near to heating source and the part away from the heating source.

For example, during boiling of water in a vessel, you can see the bubbles moving up on the surface which is nothing but Convection due to density difference. During that heating of water it is observed experimentally that the bottom-most layer the molecules remains stationary so at that portion, conduction occurs and that heat is transferred to the layers of molecule above it which is convection.

• Radiation:- Radiation is a wave phenomenon. For conduction and Convection to occur a medium is necessary but in radiation even if the medium is not present i.e VACUUM heat can transfer (IN SPACE). Radiation occurs due to change in the electronic configuration of atoms or molecules. Radiation becomes prime when the source is at a very high temperature or when there is not medium. For example, between sun and earth, the heat transfer occurs through radiation only.