Temperature Dependence of Resistivity Temperature plays a crucial role in determining the resistivity of a material. Resistivity is a material's ability to r...
Temperature plays a crucial role in determining the resistivity of a material. Resistivity is a material's ability to resist the flow of electric current, and it is inversely related to its resistance. This means that the lower the temperature, the higher the resistance of a material.
Key points:
Temperature coefficient: The resistance of a material typically increases with increasing temperature. This means that its resistivity increases when heated.
Activation energy: When a material is heated, the atoms and molecules within it vibrate more vigorously, increasing their resistance to the flow of current.
Band theory: The electronic band theory explains the temperature dependence of resistivity. According to this theory, the energy required to excite an electron from the valence band to the conduction band is higher at higher temperatures. This means that it is more difficult for electrons to flow at high temperatures, resulting in higher resistivity.
Practical applications: Temperature coefficient is a crucial parameter in various applications, including the design of resistors, heat sinks, and other electrical components. By understanding the temperature dependence of resistivity, engineers can select materials that best meet the desired electrical requirements at different operating temperatures.
Examples:
For example, the resistance of copper wire increases by about 2% per degree Celsius.
Similarly, the resistance of a light bulb filament increases when heated.
The temperature coefficient of a good conductor like aluminum is low, while that of a bad conductor like graphite is high