# Heat transfer

## Conduction

Conduction can be defined as the heat transfer through a substance because of a temperature gradient. The rate of heat transfer by conduction between two regions of a substance is proportional to the temperature difference between them. The constant of propotionality is called thermal conductivity of the material.

Mathematically, it can be described by using the Fourier's law:

$Q_{Conduction} = -k*A*\frac{dT}{dx}$

Where

$Q = \mbox{Heat conducted}\;[W]$
$k = \mbox{Thermal conductivity of the material}\;[W/m\,K]$
$A = \mbox{Cross-sectional area of the object perpendicular to heat conduction}\;[m^2]$
$T = \mbox{Temperature}\;[K]$
$x = \mbox{Length of the object}\;[m]$