Temperature coefficient of resistivity

Definition

The temperature coefficient of resistivity quantifies how much a material's electrical resistivity changes with temperature. It is typically denoted by the Greek letter alpha (α) and has units of per degree Celsius ($ \text{\degree C}^{-1} $).

5 Must Know Facts For Your Next Test

1. Most conductive materials have a positive temperature coefficient of resistivity, meaning their resistance increases with temperature.
2. Resistivity changes can be approximated using the formula $ \rho(T) = \rho_0 [1 + \alpha (T - T_0)] $, where $ \rho(T) $ is the resistivity at temperature T, $ \rho_0 $ is the original resistivity, and $ \alpha $ is the temperature coefficient.
3. Materials like semiconductors may have a negative temperature coefficient of resistivity, where resistance decreases as temperature increases.
4. The value of α varies significantly between different materials; for example, metals typically have small positive values, while insulators can have large positive or negative values.
5. Understanding the temperature coefficient of resistivity is crucial for designing electronic devices that operate efficiently under varying thermal conditions.

Review Questions

• What does a positive temperature coefficient of resistivity indicate about a material's behavior as it heats up?
• How would you use the formula involving α to find the change in resistivity when temperature changes?
• Why is it important to know the temperature coefficient of resistivity when designing electronic circuits?

Related terms

Resistivity: A measure of how strongly a material opposes the flow of electric current, usually denoted by $ \rho $. It depends on both material properties and environmental conditions.

Ohm's Law: $ V = IR $, where V is voltage, I is current, and R is resistance. This fundamental law relates voltage, current, and resistance in an electric circuit.

Conductance: The reciprocal of resistance; it measures how easily electric current flows through a material. It is denoted by G and measured in siemens (S).