How does a wire's material affect its electrical resistance?

A wire's material is a fundamental factor in determining its electrical resistance because each material possesses a characteristic property known as resistivity. Resistivity quantifies how strongly a material opposes the flow of electric current.

The resistance ($R$) of a wire is calculated using the formula:
$$R=\rho \frac{l}{A}$$
where $\rho$ is the resistivity of the material, $l$ is the length, and $A$ is the cross-sectional area.

Materials with low resistivity, such as copper and silver, are excellent conductors because they have a high density of free electrons that can move easily through the crystal lattice. In these materials, electrons occasionally collide with ions, transferring energy as heat, which constitutes electrical resistance. Conversely, insulators have extremely high resistivity because their electrons are locked into bonds and are not free to move.123

Additionally, resistivity is temperature-dependent. For metallic conductors, resistivity generally increases with temperature due to increased ion vibrations, which cause more frequent electron scattering.12