# Difference between Conduction and Convection

<p>Both <strong>conduction</strong> and <strong>convection</strong> are modes of heat transfer from one system to another. When there is a difference in the temperature of two systems, then the transfer of heat takes place from the system of higher temperature to the system of lower temperature.</p><p>In practice, this transfer of heat takes place in three different modes viz. <strong>conduction, convection</strong> and <strong>radiation</strong>. But, in this article, we will only discuss about conduction and convection and how they are different from each other.</p><p><img src="https://www.tutorialspoint.com/assets/questions/tmp/Conduction and Convection.png" class="fr-fic fr-dib" width="700" height="160"></p><h2>What is Conduction of Heat?</h2><p>When the transfer of heat takes place from one part of the substance to another part without any movement in the molecules of the substance, then it is called <strong>conduction mode of heat transfer</strong>.</p><p>In the conduction mode of heat transfer, rate of heat transfer, i.e. the rate of conduction of heat along the substance depends upon the temperature gradient. A common example of heat transfer through the conduction mode is the transfer of heat from one part of a metallic object to another part of it. The conduction mode of heat transfer is used in refractory heating, heating of insulating materials, etc.</p><h2>What is Convection of Heat?</h2><p>When the heat is being transferred from one part of the substance to another part due to the actual movement of the molecules of the substance, then this is known as <strong>convection mode of heat transfer</strong>.</p><p>In case of convection mode of heat transfer, the rate of heat transfer depends upon the difference in the density of fluid (or substance) at different temperatures. The convection of heat is mainly takes place in case of fluids. One of the common examples of convection mode is immersion water heater.</p><h2>Difference between Conduction and Convection</h2><p>The following table highlights the key differences between Conduction and Convection −</p><table class="table table-bordered"><thead><tr><th style="text-align: center;">Basis of Difference</th><th style="text-align: center;">Conduction</th><th style="text-align: center;">Convection</th></tr></thead><tbody><tr><td style="vertical-align: middle; text-align: center;">Definition</td><td>When the transfer of heat from one part of a body to another part takes place without the actual movement of molecules of the body, it is known as conduction of heat.</td><td>When heat transfers from one part of a body to another part due to actual movement of molecules of the body, then it is known as convection mode of heat transfer.</td></tr><tr><td style="vertical-align: middle; text-align: center;">State of material</td><td>Conduction mode of heat transfer is generally noticed in the solids.</td><td>The convection mode of heat transfer is noticed in the fluids and gases.</td></tr><tr><td style="vertical-align: middle; text-align: center;">Cause of heat transfer</td><td>In case of conduction, the heat transfers from one part of substance to another part due to free electrons (molecules at rest).</td><td>In convection mode, the heat transfer takes place due to actual motion of molecules.</td></tr><tr><td>Cause of occurrence</td><td>The heat transfer through conduction occurs due to the difference in the temperature of two parts or bodies.</td><td>The difference in the density of fluid at different temperatures is the cause of occurrence of the heat transfer through convection.</td></tr><tr><td style="vertical-align: middle; text-align: center;">Contact between bodies</td><td>In case of conduction mode, the heat transfer requires a direct contact between the two bodies.</td><td>In convection mode, there is no need of direct contact between two bodies but an intermediary is required.</td></tr><tr><td style="vertical-align: middle; text-align: center;">Heat transfer</td><td>In conduction mode, the heat transfers between different parts of a substance due to molecular collision.</td><td>In convection mode, the heat transfers from one part of fluid to another part due to diffusion of heated particles.</td></tr><tr><td style="vertical-align: middle; text-align: center;">Speed of heat transfer</td><td>Conduction is a slow process of heat transfer.</td><td>The convection is a relatively faster process than conduction.</td></tr><tr><td style="vertical-align: middle; text-align: center;">Direction of heat transfer</td><td>In conduction mode, the heat transfer can take place in any direction from hot to cold.</td><td>In convection mode, the transfer of heat occurs along the path of convection current in any direction from hot to cold. from source of heat to the coldest region on the top.</td></tr><tr><td style="vertical-align: middle; text-align: center;">Occurrence</td><td>In conduction mode, the transfer of heat continues until the temperatures of the bodies are equal.</td><td>In convection mode, cycle of heat transfer occurs while temperature difference exist.</td></tr><tr><td style="vertical-align: middle; text-align: center;">Examples</td><td>The heating of a metal bar when placed in high heat region is an example of heat transfer by conduction.</td><td>A common example of heating convection is the heating of water within a vessel which is placed at high flame.</td></tr></tbody></table><h2>Conclusion</h2><p>From the above discussion, we can conclude that both conduction and convection are two different modes of heat transfer, however these two methods do not obey the laws of reflection and refraction of heat.</p>