# Conduction vs Convection vs Radiation – Difference and Comparison

## What is Conduction?

It is the process in which heat energy is transferred from the hot surface end to the cold surface of an object. Conduction is the process of direct heat transfer from matter due to a difference in temperature between connected parts of an object.

When molecules’ temperature rises or increases, it causes robust vibration among molecules. The molecules collide with the surrounding molecules causing more vibrations and causing heat transfer among molecules.

It is the heat transfer through the body, not involving the radiation or flow of material. The conduction process happens when two things at different temperatures meet, and heat energy transfers from the hot object to the cold object.

Anything which allows energy to go through it is called a conductor. The best example of the conduction of heat is the frying pan on the stove. The heat from the burner directly transfers to the base of the pan.

## What is Convection?

The process of moving molecules from a hot to a cold temperature is called convection. Convection occurs only in fluids. Objects and fluids transfer heat initially by conduction, but bulk heat transfer occurs due to fluid motion.

Fluid indicates anything which has free molecules in it. It may be a liquid or gas. The process of convection happens naturally or by force. Natural convection relies heavily on gravity to heat a substance from below.

The hotter part expands as a result. In the same way, that buoyancy causes the less dense substance to rise, the more dense substance sinks at the bottom when it gets hot, and the hotter substance moves upward when it gets hotter, and so on.

In convection, its molecules disperse and move apart on heating the substance.

Radiation is a mechanism of heat transfer in which no medium is needed. The heat transfer by radiation is fastest as no molecules are involved.

In radiation, energy emission occurs in the form of waves. Objects don’t have to be in direct contact with each other for heat transfer.

Whenever you feel heat without touching any object is because of radiation. Moreover, a few properties like color, surface, and orientation can affect the radiation.

In radiation, the energy is transmitted through electromagnetic waves called radiant energy. The object that is hot releases energy to the cold objects.

The best example of radiation energy is solar radiation. We get heat from the sun even though it is miles away.

## Difference Between Conduction, Convection, and Radiation

Through direct physical contact, conduction transports heat between parts of a continuum. Heat is transferred by convection through currents in fluids, such as liquids or gases. Electromagnetic waves are used to carry heat through radiation.

Conduction represents that heat is transferred between two objects by direct contact, while in convection, heat is transferred by colliding molecules. in contrast to both in radiation, no medium is required for heat transfer.

## References

Dai; et al. (2015). “Effective Thermal Conductivity of Submicron Powders: A Numerical Study.” Applied Mechanics and Materials. 846: 500–505. doi:10.4028/www.scientific.net/AMM.846.500. S2CID 114611104.