One-dimensional steady-state heat conduction through a multi-layered composite plane wall is governed by Fourier's law. In direct analogy to electrical Ohm's law, the constant heat flux passing through layers in series is driven by the total overall temperature difference divided by the sum of individual layer conductive thermal resistances (R_th = L / (k·A)). The temperature profile drops linearly within each material, with steeper temperature gradients occurring in lower thermal conductivity layers.