Question

Experimental investigation determining the thermal conductivity for three different materials, silver painted zincalume, acrylic and black timber. Expected that zincalume would have the highest conductivity followed by acrylic and then timber (best insulator).

Results found the opposites where timber had the highest conductivity (k= 0.317) then acrylic (k=0.307) and zincalume (k=0.303)

How do I scientifically explain these results using the theory of heat transfer?

Answer 1

It is not always true that a material which has high electrical conductivity also is good conductor of heat.To be a good electrical conductor, it is important to have free electrons. While to be good conductor of heat it is required for atoms to be close enough to transfer heat by vibrations.

Silver painted zincalume is good conductor of electricity because it has free electron while timber does not have free electron so it is insulator. But the atoms of timber is closely spaced whose vibrations are responsible for conduction of heat. Hence, thermal conductivity of timber is more than silver painted zincalume.