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Difference between conduction, convection and radiation

While there conduction the transfer of thermal energy by direct contact, the convection the movement of heat for the real movement of matter; radiation the transfer of energy with the help of electromagnetic waves.

The issue around us, in three states, solid, liquid and gas. The conversion of matter from one state to another defined as a change of state, which occurs because of the exchange of heat between matter and its surroundings. Hence, the heat transition of energy from one system to another, due to the difference in temperature, which occurs in three different ways, which are conduction, convection and radiation.

People often misunderstand, these forms of heat transfer but, they are based on different physical interactions to transfer energy. To study the difference between conduction, convection and radiation, let's take a look at the article provided below.

Comparative chart

Basis for comparison ConductionConventionRadiation
SenseConduction is a process in which heat transfer occurs between objects by direct contact.Convection refers to the form of heat transfer in which the energy transition takes place within the fluid.The radiation refers to the mechanism in which heat is transmitted without any physical contact between objects.
To representHow heat travels between objects in direct contact.How heat passes through liquids.How heat flows through empty spaces.
CauseDue to the temperature difference.Due to the difference in density.Occurs from all objects, at temperatures above 0 K.
occurenceIt occurs in solids, through molecular collisions.It occurs in fluids, from the actual flow of matter.It occurs remotely and does not heat the interposed substance.
Heat transferUse heated solid substance.Use intermediate.Use electromagnetic waves.
speedSlowSlowFast
Law of reflection and refractionIt does not followIt does not followFollow

Definition of conduction

Conduction can be understood as the process, which allows the direct transfer of heat through matter, due to the temperature difference, between adjacent parts of the object. It happens when the temperature of the molecules present in a substance increases, resulting in a vigorous vibration. The molecules collide with the surrounding molecules, making them vibrate also, with the consequent transfer of thermal energy to the nearby part of the object.

In simple terms, whenever two objects are in direct contact with each other, there will be a transfer of heat from the hottest object to the coldest one, which is due to conduction. In addition, objects that allow heat to travel easily through them are called conductors.

Definition of convection

In science, Convection involves the form of heat transfer, through the real movement of matter, which occurs only in fluids. The fluid alludes to any substance whose molecules move freely from one place to another, such as liquids and gases. It happens naturally or even forcefully.

Gravity has a great role to play in natural convection so that when the substance is heated from below, it leads to the expansion of the hottest part. Due to the buoyancy, the warmer substance increases because it is less dense and the colder substance replaces it sinking in the lower part, due to the high density, which when it warms up moves and the process continues. In convection, by heating the substance, the molecules disperse and move away.

When convection is performed forcefully, the substance is forced to move upward by any physical means such as the pump. Eg Air heating system.

Definition of radiation

The heat transfer mechanism in which no means called radiation are required. It refers to the movement of heat in waves, as it doesn't need molecules to travel through. The object must not be in direct contact with each other to transmit heat. Whenever you feel the heat without actually touching the object, because of radiation. In addition, the color, the orientation of the surface, etc. These are some of the surface properties on which radiation depends a lot.

In this process, energy is transmitted through electromagnetic waves called radiant energy. Hot objects generally emit thermal energy in colder environments. Radiant energy capable of traveling in a vacuum from its source to the colder surroundings. The best example of radiation is the solar energy we get from the sun, even if it is miles away from us.

Key differences between conduction, convection and radiation

The substantial differences between conduction, convection and radiation are explained as below:

  1. Conduction is a process in which heat is transported between the parts of a continuum, through direct physical contact. Convection is the principle in which heat is transmitted by currents into a fluid, ie liquid or gas. Radiation is the heat transfer mechanism, in which the transition occurs through electromagnetic waves.
  2. Conduction shows how heat is transferred between objects in direct contact, but convection reflects how heat travels through liquids and gases. In contrast, radiation indicates how heat travels through places without molecules.
  3. Conduction occurs as a result of the temperature difference, i.e. heat flows from a high temperature area to a low temperature area. Convection occurs due to the variation in density, so that the heat moves from the low density region to the high density region. In contrast, all object release heat has a temperature above 0 K.
  4. Conduction usually occurs in solids, through molecular collision. Convection occurs in fluids with the mass movement of molecules in the same direction. On the contrary, the radiation occurs through the vacuum of space and does not heat the intermediate medium.
  5. The heat transfer takes place through the heated solid substance, in conduction, while in convection the thermal energy is transmitted through an intermediate medium. In contrast, the ration uses electromagnetic waves to transfer heat.
  6. The speed of conduction and convection slower than radiation.
  7. Conduction and convection do not follow the law of reflection and refraction, while radiation obeys in the same way.

Conclusion

Thermodynamics the study of heat transfer and related changes. Conduction is nothing more than the transfer of heat from the warmest to the coldest part. Convection is the transfer of heat through the up and down movement of the fluid. Radiation occurs when heat travels through empty space.