Fourier’s Law of Conduction states how much heat shall flow through a conductor bridging a thermal difference. This law was formulated by Joseph Fourier in 1822. 
Specifically, Fourier’s Law states that heat flow is proportional to the conductor’s area and the thermal difference bridged, and is inversely proportional to the conductor’s length.
Use the following simulation to try out Fourier’s Law. (The simulation may take a moment to load).
1. Davies, T.W., “Fourier’s Law“, Thermopedia.com.