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Heat conduction at microscopic level
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Phonons and electrons carry heat.
In metals free electrons carry most heat (hence Wiedemann–Franz law); in insulators, phonons carry it. Impurities and boundaries scatter carriers and reduce conductivity.
Diamond conducts heat very well via phonons.
Thermal conductivity depends on mean free path.
In more detail
At the microscopic level, heat conduction results from energetic molecules transferring energy to slower neighbours through collisions and electron motion in metals.
Real-world uses
- Understanding why metals conduct heat better than insulators.
- Nanoscale heat transfer depends on microscopic processes.
- Engineers designing heat sinks for electronics rely on heat carried by lattice vibrations and electrons.
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Frequently asked questions
Do electrons conduct heat?
Yes, in metals free electrons carry much of the thermal energy.
Why are gases poor conductors?
Their molecules are far apart, so energy transfers only during rare collisions.
Which carries heat better, electrons or vibrations?
In metals, electrons usually carry most of the heat, while in insulators lattice vibrations are the main carriers.
Related topics in Kinetic Theory & Statistical Physics
Planck distribution · Random walks · Equation of state of ideal gas in statistical terms · Transport phenomena · Phase transitions · Ising model