Which class of materials exhibits decreased electrical conductivity with increasing temperature?

The class of materials that exhibits decreased electrical conductivity with increasing temperature is indeed associated with certain types of semiconductors, particularly P-type and N-type, but the focus here is on how metals behave in response to temperature changes.

In metals, as the temperature increases, the lattice vibrations become more intense. These vibrations cause increased scattering of conduction electrons, which in turn raises the resistance of the metal. Since electrical conductivity is inversely related to resistance, this results in a decrease in conductivity as the temperature goes up. This behavior is a characteristic of metallic conductors, where free electrons are abundant and are significantly affected by thermal agitation.

In contrast, semiconductors, including both P-type and N-type, behave differently. For these materials, increasing temperature typically generates more charge carriers (either holes in P-type or electrons in N-type), thus increasing their electrical conductivity with temperature. This distinction is crucial as it highlights the unique properties of metals compared to semiconductor materials.

Understanding these fundamental differences helps clarify why metals would exhibit a decrease in electrical conductivity with rising temperature, aligning with the principles governing conduction in metallic materials and their thermal sensitivities.