What is Conduction?
The process of heat transfer in which heat is transmitted from one portion of the body at a higher temperature to another area of the body at a lower temperature without the molecules moving from one place to another is known as conduction.
Conduction occurs most in solids as a result of temperature differences. It happens due to free electron energy transfer and molecular lattice vibrational energy transmission.
Free electrons are responsible for 70% of heat transfer, whereas vibration is responsible for the remaining 30%. When one end of a metal rod is heated, the other end eventually becomes heated as well.
What is Convection?
Convection, unlike conduction occurs in liquids and gases. It is the transfer of heat through the movement of particles. Warm particles rise, and cool particles fill in the space below, so this is a circular motion.
Natural, forced, gravitational, granular, or thermomagnetic convection are all possible classifications.
When we heat a pot of water, the water particles at the surface heat up first; we know that heat causes particles to travel faster. Therefore these particles move randomly and a relatively space is formed. Particles from far locations migrate here to fill the space. Again, these particles require heat energy and go away, and the process repeats itself, resulting in hot water from cold water.
What is Radiation?
Heat energy can also be transported without particles, allowing it to pass across a vacuum. This occurs when power is delivered through radiation, specifically infrared wavelengths.
All objects are capable of both absorbing and emitting radiation at the same time. The hotter something is, the more radiation it emits.
This is why putting your hand over a grill feels hot even if you aren’t touching it. Infrared radiation is emitted by the scorching metal and coal absorbed by your hand. When we look at infrared radiation in the context of the electromagnetic spectrum, we can see how it is.
Difference Between Conduction, Convection and Radiation
- The presence of a medium is required for heat conduction and convection. Radiative heat transfer, on the other hand, does not require the usage of a medium.
- Conduction and convection are impossible in a vacuum, but radiation is feasible.
- In conduction, heat can be moved in any direction, whereas heat can only be transferred vertically upward in convection. Radiation is a method of transferring heat in a straight line in all directions.
- Conduction is a slow process, whereas convection is quicker than conduction, and the process is the quickest, with heat transfer occurring at the speed of light in case of radiation.
- Conduction requires heated solids, while convection necessitates the use of fluids, and radiation necessitates the use of electromagnetic waves as a medium.
Comparison Between Conduction, Convection and Radiation
| Parameters of Comparison | Conduction | Convection | Radiation |
| Medium | Conduction of heat requires the presence of a medium. | For heat transfer by convection, a medium is required. | The use of a medium is not required for radiant heat transmission. |
| Vacuum | In a vacuum, conduction is not possible. | In a vacuum, convection is not possible. | In a vacuum, radiation can happen. |
| Effects on medium | The medium particles do not deviate from their average location. They dissipate heat by vibrating around their centre of gravity. | The medium particles leave their average position and migrate upward, transporting heat from the source. | The medium is unaffected in any way. |
| Direction of heat | Heat can be transferred in any direction. | The only way for heat to be transferred is vertically upward. | Heat is transferred in all directions in a straight line. |
| Time taken | The process is slow. | The process is faster than conduction. | The process is the fastest and the transfer of heat takes place with the speed of light. |