What is the Difference Between Electrical and Thermal Conductivity?

Electrical conductivity and thermal conductivity are two distinct physical properties of materials. The main differences between them are:

1. Definition: Electrical conductivity is a measure of how well an electrical current (charge in motion) can pass through a material under the influence of an applied voltage/electric field. Thermal conductivity, on the other hand, measures how well heat (thermal energy in motion) can pass through a material under a temperature differential.
2. Mechanism: Electrical conductivity is primarily due to the movement of electrons in a material, while thermal conductivity is due to the vibration or oscillation of atoms or molecules.
3. Relationship in Metals: In metals, the Wiedemann-Franz law states that thermal conductivity is inversely proportional to electrical conductivity. This means that if one of these properties is high, the other is usually low.
4. Material Dependence: While electrical conductivity is virtually nonexistent in non-metals, thermal conductivity can vary depending on the atomic arrangement and crystalline structure. For example, compounds of pure carbon have varying degrees of conductivity, which can differ by an order of magnitude depending on the atomic arrangement.

In summary, electrical conductivity is related to the flow of electrical current through a material, while thermal conductivity is related to the transfer of heat energy within a material. These properties are influenced by different mechanisms, and their relationship in metals can be described by the Wiedemann-Franz law.

Comparative Table: Electrical vs Thermal Conductivity

Here is a table comparing the differences between electrical and thermal conductivity:

In summary, electrical conductivity is related to the flow of electric current, while thermal conductivity is related to the transfer of heat. Both properties depend on the motion of charged particles (electrons) and the vibration of the lattice structure. The ratio of thermal to electrical conductivity depends on temperature and other properties in metals, as described by the Wiedemann-Franz Law.