Question

Brass is a metal consisting principally of copper alloyed with a smaller amount of zinc, whose atoms do not alternate in a regular pattern in the crystal lattice but are somewhat randomly scattered about. The resistivity of brass is higher than that of either copper or zinc at room temperature, and it drops much slower as the temperature is lowered. What do these behaviors tell us about electrical conductivity in general?

Short answer

Conductivity grows slowly as the temperature falls, unlike copper or zinc.

Step-by-step solution

Concept:

The valence electron becomes a free electron and thus the metal can conduct electricity. Thus, the electrical conductivity of copper increases with increasing temperature because the electrical conductivity of a metal is caused by the movement of electrons.

Step 2: Electrical conductivity:

Collisions between electrons and positive ions do not generate resistance in metals. Instead, the variation from regularity disrupts the electron wave, determining the metal's resistance. Brass, which is made up of atoms that do not alternate in a regular manner, has a far higher resistance than copper or zinc. This is due to the regular crystal pattern of copper or zinc.

The resistance of a metal increases as temperature rises and reduces as the temperature falls due to the vibration of the positive ions in the metal. The resistivity of brass is caused by flaws in the metal and is nearly temperature independent. As a result, as the temperature is dropped, the resistance of brass gradually diminishes. As a result, compared to copper or zinc, its conductivity rises slowly as the temperature decreases.

Hence, conductivity grows slowly as the temperature falls, unlike copper or zinc.