Resistivity

Definition

Resistivity is a material property that quantifies how strongly a given material opposes the flow of electric current. It is denoted by the Greek letter $\rho$ (rho) and measured in ohm-meters ($\Omega \cdot m$).

5 Must Know Facts For Your Next Test

1. Resistivity depends on both the type of material and its temperature.
2. The formula relating resistivity ($\rho$), resistance ($R$), length ($L$), and cross-sectional area ($A$) is $R = \rho \frac{L}{A}$.
3. Materials with low resistivity are good conductors, such as copper and aluminum, while materials with high resistivity are insulators like rubber and glass.
4. For most conductors, resistivity increases with temperature due to increased atomic vibrations.
5. Semiconductors have resistivities that decrease with increasing temperature due to an increase in charge carriers.

Review Questions

• What is the relationship between resistivity, resistance, length, and cross-sectional area?
• How does temperature affect the resistivity of most conductors?
• Why do semiconductors exhibit decreasing resistivity with increasing temperature?

Related terms

Resistance:

The opposition to the flow of electric current, measured in ohms ($\Omega$).

Conductivity:

A measure of a material's ability to conduct electric current; it is the reciprocal of resistivity.

Ohm's Law:

$V = IR$, where $V$ is voltage, $I$ is current, and $R$ is resistance.