Question

Comment on the statement. The thermal conductivity of solid metals increases with the rise in temperature.

Answer 1

Hint: As we know that the thermal conductivity of a material is described as a measure of its ability to conduct heat. When heat is transferred, it occurs at a lower rate in materials of low thermal conductivity whereas it occurs at a higher rate in materials of high thermal conductivity.

Complete answer:
Let us understand about thermal conductivity followed by the explanation of the given statement in the question as follows:-
-Thermal conductivity: It can be described as a measure of material’s ability to conduct heat. When heat is transferred, it occurs at a lower rate in materials of low thermal conductivity whereas it occurs at a higher rate in materials of high thermal conductivity.
-The thermal conductivity of any material is mainly dependent on two things which are:-
(A) Motion of electrons in the material
(B) Molecular vibrations
-In case of metals, the thermal conductivity is mainly the function of motion of free electrons. When the temperature of the metal is increased, the molecular vibrations increase which in turn decreases the mean free path of the electrons in it. Hence, they obstruct the flow of free electrons with the increment in temperature, thus reducing the conductivity of heat in metals.
-Therefore we can say that, the above given statement is false as the thermal conductivity of solid metals decreases with the rise in temperature.

Note:
-Remember that in case of non-metals, there are no free electrons and therefore only the molecular vibrations are responsible for conduction of heat. For non metals, the conductivity increases as we increase the temperature.