## Conduction is the transfer of heat through a body without displacement of the particles which make up the body

Conduction is the transfer of heat through a body without displacement of the particles which make up the body. This means that all of the particles of the body or system must stay in place as heat is allowed to flow through. An example of this is boiling water in a tin can over an open flame. The tin can gets heat from the fire through radiation. However, the tin can pass the heat from the fire and transfer it to the water through conduction. The particles in the tin are not displaced during or after the heat transfer. Fourier’s Law states that the time it takes for the heat to flow across a unit area at steady state is proportional to the temperature gradient orthogonal to the area. The thermal conductivity of the material (K) refers to the difficulty in which the heat transfers through a material. The value of K can vary from about 0.01 W/mK for gases to 1000 W/mK for pure metals. It is dependent on a few variables such as temperature, bonding and structure of the material. This means that metals would have the highest thermal conductivity when compared to polymers and ceramics. This is due to the sea of electrons in metals which allows the heat to transfer through easier. The sea of electron refers to the metallic bonding of the material. As a result, metals can also withstand higher temperatures compared to polymers and ceramics (for most cases). In addition, thermal conductivity is lowered when the material is porous. The variation of thermal conductivity with temperature can be described by the equation below.

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