text: The law of heat conduction, also known as Fourier's law, states that the rate of heat transfer through a material is proportional to the negative gradient in the temperature and to the area, at right angles to that gradient, through which the heat flows. We can state this law in two equivalent forms: the integral form, in which we look at the amount of energy flowing into or out of a body as a whole, and the differential form, in which we look at the flow rates or fluxes of energy locally.
  Newtons law of cooling is a discrete analogue of Fouriers law, while Ohms law is the electrical analogue of Fouriers law and Fick's laws of diffusion is its chemical analogue.