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Q & A: Thermal and Electrical Conduction

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Most recent answer: 06/13/2012
hi i was wondring if it was a coincidence that good electrical conductors are good heat conductor? if so what is the relationship?
- Anonymous
There is a reason why most good electrical conductors also conduct heat well. However, the relationship only holds, to a good approximation, in metals. Both electrical and thermal conduction in metals occur mainly via the free electrons. The relationship between electrical conductance and thermal conductance is known formally as the

Both types of conductivity are proportional to how many free electrons are present, how fast they typically move, and how far they travel before scattering off in a new direction.

Generally speaking though, there is no real relation between how well a material conducts heat and how well it conducts electricity unless it's a metal.  For other materials the heat conduction usually occurs mainly via high-frequency sound waves in the material, not by the electrically charged electrons.  For example, the lattice structure of diamonds conducts heat very well, but the same structure also makes them generally very good electrical insulators.

-Matt J. +mbw

(published on 01/14/2012)

Follow-Up #1: How is heat conducted?

briefly with molecular theory explain why most metals are good conductors of heat while non-metals are good insulators ?
- cuthbert (age 15)
Cuthbert- Your question was close enough to several previous questions to be marked as a follow-up.

Although the free electrons in metals do a good job of conducting heat, some insulators also conduct heat well. In those insulators, sound waves travel around easily enough to conduct the heat well.

Mike W.

(published on 06/13/2012)

Follow-up on this answer.