Alexander Fufaev
My name is Alexander FufaeV and here I will explain the following topic:

Wiedemann-Franz Law: How Electrical and Thermal Conductivity Are Related

Formula

Formula: Wiedemann-Franz Law
What do the formula symbols mean?

Thermal Conductivity

Unit
Thermal conductivity is the specific thermal conductivity of the conductor, which depends on the geometry of the conductor (hence "specific"). This tells how capable a conductor is of transporting heat.

Electrical Conductivity

Unit
Electrical conductivity is the specific electrical conductivity of the conductor, which depends on the geometry of the conductor (hence "specific"). This tells how well a conductor conducts the electric current.

Lorenz number

Lorenz number is the constant of proportionality between the temperature and the ratio of conductivities. The unit of Lorenz number is \( \mathrm{V}^2 / \mathrm{K}^2 \).

Temperature

Unit
Absolute temperature of the considered material.
Explanation

Video

The Wiedemann-Franz law is an empirical relationship between the electrical conductivity \( \sigma \) and the thermal conductivity \( \kappa \) of a metal at constant temperature \( T \).

Formula anchor

Here \( L \) is the Lorenz number. It is the proportionality constant between the temperature and the ratio of the conductivities. The unit of the Lorenz number is \( \mathrm{V}^2 / \mathrm{K}^2 \).