Thermal conductivity (λ) represents what type of heat flow through a material?

Thermal conductivity (λ) is a measure of a material's ability to conduct heat through conduction. Conduction is the process where heat energy is transferred through direct contact of particles within a solid or between solids in contact, without any movement of the material as a whole. This heat transfer occurs at the microscopic level as vibrating particles collide with neighboring particles, passing the energy along.

When a temperature gradient exists within a material, heat will flow from the hotter region to the cooler region through conduction, and this flow rate is quantified by the thermal conductivity. The higher the thermal conductivity of a material, the more efficient it is at conducting heat.

In contrast, convective heat flow involves the movement of fluid (liquid or gas) that carries heat with it, radiant heat flow pertains to the transfer of energy through electromagnetic waves (such as infrared radiation), and evaporative heat flow is associated with the heat absorbed or released during phase changes of a substance. These processes do not directly involve the conduction mechanisms described by thermal conductivity.