We explain that what is the difference between conduction, convection, and radiation with the table. When thermal energy is transferred from one system to another by dispersing heat, the phenomenon is called heat transfer.
This can be done in three ways: conduction, convection, and radiation.
The key difference between conduction, convection and radiation lies in the fact that it is just a matter of how heat is transferred from an area with higher kinetic energy to an area with lower kinetic energy.
In driving, this happens through direct physical contact between two objects.
Convection, on the other hand, occurs when heat is transferred through the motion of molecules.
It refers to the heat transfer that occurs in fluids. Radiation does not require physical contact between two objects like the other methods.
It is the process by which heat is transferred through electromagnetic waves.
Comparison table between conduction convection and radiation
Comparison parameter Conduction Convection Radiation
| Definition | Process of heat transfer between objects through direct physical contact. | Heat transfer process through a fluid medium such as liquids or gases. | Heat transfer process through electromagnetic waves. |
| Method | Heat is transferred due to molecular collision when solids come into contact with each other. | Heat is transferred by the flow of fluids. | Heat is transferred through radiation emitted by bodies without the need for a medium. |
| Because | Heat traveling from a high temperature area to a low temperature area. | Heat traveling from a low-density area to a high-density area. | Energy emitted by bodies through the rotational and vibrational movements of atoms and molecules. |
| Half | Heated solids. | Intervening substance such as fluids. | Electromagnetic waves. |
What is conduction?
The process of heat transfer through direct contact between two objects is called conduction.
When the molecules of an object absorb heat energy, they begin to move rapidly, and in doing so they come into contact with neighboring objects and a transfer of energy occurs.
Driving is a very common process. Simply touching a hot container causes conduction to occur and heat is transferred from the container to your hand.
For driving to happen, a few factors must be taken into account.
The first is the temperature gradient, which is the description of the direction in which the heat flows and the rate of transfer.
The process of conduction from a hot source to a cold one (or a source that lacks thermal energy) continues until both bodies reach a state of thermal equilibrium.
Another important factor is the size of the objects involved. Larger objects require more heat to warm up, but at the same time, they lose heat faster.
This is because the larger their surface area, the more they come into contact with the open air.
The physical properties of objects must also be taken into account.
If you use a wooden spoon while cooking, you will notice that the spoon does not heat up. This is because wood is a poor conductor.
However, if you were to use a metal spoon, the heat will transfer to you very quickly because metal is a good conductor.
Poor conductors are also called insulators.
They prevent energy from flowing away from the source.
For example, polar bears can survive in arctic regions because their fur serves as an insulator that traps heat within the body.
What is convection?
When the mass movement of a fluid occurs as the heated fluid moves away from the heat source, it carries energy with it. This is also a form of heat transfer and is called convection. This process occurs because heat decreases the density of fluids such as air and water.
The loss of density causes the fluid to rise to create convection currents that can transfer energy.
As the hot layers of the fluid rise, the cooler layers that still retain their density move down toward the heat source until they warm up and begin to rise.
There are two types of convection: spontaneous and forced. In the former, convection occurs naturally due to buoyancy.
The difference in temperature causes a difference in densities.
For example, when the sun’s heat warms the land, the sea absorbs most of the energy, but it takes longer to warm up than the land.
Therefore, the air above the land loses density more rapidly, leading to the creation of an area of low pressure over the coastal areas.
But the area over the sea has a higher pressure and this causes the air to move from the area of higher pressure to the area of lower pressure, that is, from the sea to the land.
Therefore, the breeze near the sea is generally stronger.
Forced convection is produced by an external source such as a fan or a geyser.
It is related to Newton’s law of cooling the equation for which is the following:
P = dQ / dt = hA (TT)
Here P = dQ / dt is the rate of heat transfer. The h is the convection heat transfer coefficient. A is the surface area of the material that is exposed.
T refers to the temperature of the object in the fluid and T refers to the temperature of the fluid undergoing the convection process.
See Also: Dot Product Vs Cross Product
What is radiation?
Unlike conduction and convection, which require actual physical contact between two bodies, radiation is the transfer of heat that occurs even when the bodies do not come into contact or are separated in space.
Everything in the universe is made up of atoms that together form molecules.
The rotation and vibration of atoms and molecules ensure that all substances continue to emit energy through electromagnetic radiation.
Electrons with high energy at high atomic levels descend to levels where the energy is lower.
Any energy lost along the way is emitted as electromagnetic radiation.
When energy is absorbed by an atom, its electrons rise to higher energy levels.
Therefore, when the rate at which energy is absorbed is balanced by the rate at which it is emitted, the temperature of the substance will not change.
If the first is higher than the second, the temperature will increase and if it is lower, the temperature will also decrease.
A common example of radiation heat transfer is the sun. It does not come into contact with any of the other planets, nor is there a physical medium for heat transfer.
However, we can feel its heat due to the electromagnetic radiation it emits, which allows its rays to reach the earth.
Main differences between conduction convection, and radiation
- Conduction is the process by which heat is transferred between two objects through direct physical contact.
- In convection, heat is transferred through a fluid medium, such as a liquid or a gas.
- The transition of heat through electromagnetic waves is called radiation.
- Heat traveling from a high-temperature area to a low-temperature area is the cause of conduction.
- Heat moving from a low-density area to a high-density area causes convection.
- Radiation occurs because the rotational and vibrating movements of the atoms and molecules that make up bodies cause energy to be constantly transmitted.
Conduction, Convection, and Radiation Frequently Asked Questions (FAQ)
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What are some examples of radiation conduction and convection?
Some examples of convection are boiling water, melting ice, the radiator mechanism, a steaming cup of tea, etc.
Examples of driving are using the heating pad to warm the body, the engine getting hot due to moving parts, grilling food over a campfire, etc. Examples of radiation include burning radiation emitted by candles, radiation emitted by the sun.
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Is rubbing your hands a driving?
Conduction is a phenomenon in which heat is transferred from one part to another. But in the case of rubbing hands, the heat is generated by the process of friction, rather than by conduction.
When both palms rub together, friction is created which results in the generation of heat.
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How does heat travel by conduction?
Let’s take an example of a 4-foot-long steel rod. When we start to heat the rod from one end using fire, it can be seen that the heat begins to travel through the rod and after a while the whole rod becomes hot.
This is because the material from which the rod is made has the ability to transfer heat and is a conductive material.
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Is an iron an example of conduction?
Yes, iron is an example of conduction. When you start to heat one end of a bar or piece of iron, you can see that heat begins to travel through the bar and after a while, the entire bar heats up.
This is because the material from which the rod is made has the ability to transfer heat and is a conductive material.
- Why is convection faster than conduction?
Convection is faster than the conduction process.
This is because, in the case of convection, which occurs mainly in fluids, the molecules have the freedom to move and vibrate from their places at a faster rate, while in conduction, the molecules do not have much room to move and vibrate.
- Is conduction more efficient than convection?
No, conduction is no more efficient than convection. This is because, in the case of convection, which occurs mainly in fluids, the molecules have the freedom to move and vibrate from their places at a faster rate, while in conduction, the molecules do not have much room to move and vibrate.
- How can we prevent convection?
Insulating material has been widely used around the world to reduce the effect of conduction, as these materials do not conduct heat or electricity through them and do not cause heat or energy losses.
These materials further prevent air circulation through them, which also prevents convection.
Final Thought
Conduction, convection, and radiation are important concepts in the study of thermodynamics.
Simply put, heat that travels from a hot object or hot area to a cold object in the area is conduction.
Heat is transferred through the movement of fluid currents by convection and heat is transferred through electromagnetic waves without any medium is radiation.
