# Why is it that the heat transfer is proportional to the temperature gradient?

In a thermal conduction context and according to this formula : $\varphi=\frac{\Delta T}{R_{th}}$, the heat transfer is proportional to the temperature gradient.

How does one physically explain the mecanism leading to that ? (At a microscopic pov maybe).

• Think about a stick with two different temperatures at either end. What does temperature signify to you at a microscopic poy and think about what would be the situation of the atoms/molecules of the stick at either end. Also I think it is the rate of heat transfer and not heat transfer that is proportional to the temperature gradient....right ;) – ubuntu_noob May 6 '17 at 1:02