What is the difference between conduction, convection, and radiation?
Heat transfer is the change of energy between two bodies due to different temperatures. It takes place in the form of conduction, convection, and radiation to result in heat balance.
The lesson provides the core difference between conduction, convection, and radiation in tabular form. We have also highlighted the similarities between conduction, convection, and radiation.
What Is Conduction?
Conduction is the transfer of heat through direct contact of matter due to temperature gradient. The mode of heat transfer is quite common in solids and negligible in liquids.
The most wonderful thing is that heat transfer as a result of conduction travels through a medium without transport of the mass.
The heat transfer moves from one particle to another while the substance remains idle. The mode of heat transfer occurs in homogeneous non-conductive hard bodies.
Examples of the situation with conduction:
- Touching a stove and being burned
- Ice cooling down your hand
- Boiling water by thrusting a red-hot piece of iron into it
What Is Convection?
Convection is a mode of heat transfer that involves the movement of molecules from a warm region to a cooler region. The heat transfer mode is quite common in fluids.
The mode of heat transfer occur naturally or can even be forceful. Natural convection is controlled by gravity.
Examples of situations with convection:
- Hot air rising, cooling, and falling (convection currents)
- An old-fashioned radiator (creates a convection cell in a room by emitting warm air at the top and drawing in cool air at the bottom).
What Is Radiation?
Radiation is a mode of heat transfer that occurs through electromagnetic waves without involving any medium.
The most wonderful thing is that the heat does not burn and it does not require any physical contact of the flow of particles to be transmitted.
However, the mode of heat transfer follows the law of reflection and the law of refraction. It normally occurs due to a slight increase in temperature. It happens in all states of matter.
Examples of situations with radiations:
- The heat from the sun warming your face
- The heat from a lightbulb
- The heat from a fire
- The heat from anything else which is warmer than its surroundings.
Comparison Chart: Conduction Vs Convection Vs Radiation
| Conduction | Convection | Radiation |
| Heat transfer takes place through direct contact of objects | Heat transfer occurs within the fluid | Heat transfer occurs through electromagnetic waves without involving particles |
| Heat transfer occurs due to temperature change | Heat transfer occurs due to density changes | Heat transfer takes place in all state of matter due to the temperature being greater than 0 K |
| Transfer of heat is slow | Transfer of heat is faster | Transfer of heat is the fastest |
| Occur through heat solids | Occur through fluids such as gases and liquids | Occur through the electromagnetic wave |
| Do not obey the law of reflection and refraction. | Do not follow the law of reflection and refraction. | Obey the law of reflection and refraction. |
| It represents how heat travels between objects in direct contact | Represent how heat passes through fluids | Represent the flow of heat through empty space |
| Occur in solids through molecular collision | Occur in fluids through the actual flow of matter | Occur at a distance without intervening substance. |
Core Differences Conduction, Convection, and Radiation
- Conduction is the transfer of heat in solids through direct contact whereas convection is the transfer of heat within fluids and radiation is the transfer of heat through electromagnetic waves.
- Conduction occurs in solids whereas convection in fluids and radiation in all states of matter.
- Conduction is slower while convection is faster and radiation is the fastest
- Radiation obeys the law of reflection and refraction while both conduction and convection do not follow the law.
- Conduction heat transfer takes place due to temperature differences while convection due to density differences and radiation due to the temperature being greater than 0 K.
- Conduction occurs in solids due to molecular collision whereas convection in fluids due to flow of molecules and radiation occurs in empty space without heating the intervening medium.
Similarities Between Conduction, Convection, and Radiation
- Both are mode of heat transfer
- Both occur due to differences in temperature
- Both happen on earth
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Comparison Video
Summary
Conduction occurs due to temperature gradient while convection due to the flow of molecules triggered by density differences and radiation due to electromagnetic waves.
Understanding the core difference between conduction, convection, and radiation with examples is quite vital for exam preparation.
More Sources and References
- Heat Transfer. Wikipedia
- Thermal Conduction, Convection, and Radiation. Khan Academy