Fourier’s law of heat conduction

Fourier's law of heat conduction describes how heat moves through a material without the material itself moving. This process, known as thermal conductivity, is measured in watts per meter kelvin (W/mK) and is represented by the symbol k or λ in physics. The law states that the rate of heat transfer (q) is proportional to the negative temperature gradient (∇T) and the thermal conductivity (k): q = –k∇T.1

Heat conduction occurs due to the agitation and contact between particles in a substance. In solids, heat moves from areas of high temperature to low temperature until thermal equilibrium is reached. This transfer is fastest in solids and slowest in gases due to the distance between particles. French mathematician Joseph Fourier developed this theory, which has applications beyond heat conduction, influencing mathematical physics and the study of functions.12