Fourier's law is a fundamental principle in thermodynamics and heat conduction that describes how heat propagates through a conducting material. This law was formulated by Joseph Fourier, a French mathematician and physicist, in 1822. Fourier's law is often used to analyse heat flow and predict how temperature will change over time in a structure or object. Fourier's law states the following: The heat flow (Q) through a material is directly proportional to the cross-sectional area (A) through which the heat propagates, the temperature difference between two sides of the material (ΔT) and the inverse of the distance (d) between these two sides: Q = -k * A * ΔT / where: - A is the cross-sectional area through which the heat propagates (in square metres, m²). - ΔT is the temperature difference between the two sides of the material (in degrees Celsius, °C or in kelvins, K). - d is the distance between the two sides of the material through which heat conduction takes place (in metres, m). - k is the thermal conductivity of the material (in watts per metre per kelvin, W/(m-K)). Fourier's law provides an equation that describes how heat propagates through a conducting material, such as a solid. The greater the temperature difference between the two sides of the material, the greater the heat flow. At the same time, the higher the thermal conductivity of the material, the easier it is for heat to propagate through it. Fourier's law is applied in a wide range of situations, from the thermal design of electronic devices to predicting the heating or cooling of buildings, to analysing heat diffusion in industrial processes. It provides a fundamental basis for understanding and controlling heat conduction in a variety of contexts.