Question #206323

) State and prove Wiedemannâ€“Franz law (or) Derive expressions for electrical and thermal conductivities on the basis of classical free electron theory and deduce the value of Lorentz number

Expert's answer

The ratio of a metal's thermal conductivity (K) to its electrical conductivity () is proportional to the metal's absolute temperature.

Using the formulas for electrical and thermal conductivity of metals, we can drive Widemann-Franz's law using classical theory.

The expression for thermal conductivity

The expression for elecetricl conductivity

We know that kinetic energy s given by

L is the Lorentz number

As a result, it is demonstrated that the ratio of a metal's thermal and electrical conductivity is proportional to the metal's absolute temperature.

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