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002 Temperature Coefficient of Resistance (TCR)

The resistance thermal coefficient, also known as the temperature coefficient of resistance (TCR) or resistance temperature coefficient (RTC), describes how a material's electrical resistance changes with temperature. It's a crucial parameter for understanding and predicting the behavior of resistors and other electronic components in varying thermal conditions. The “alpha” (α) constant is known as the temperature coefficient of resistance and symbolizes the resistance change factor per degree of temperature change. Just as all materials have a certain specific resistance (at 20° C), they also change resistance according to temperature by certain amounts. For pure metals, this coefficient is a positive number, meaning that resistance increases with increasing temperature. For the elements carbon, silicon, and germanium, this coefficient is a negative number, meaning that resistance decreases with increasing temperature. For some metal alloys, the temperature coefficient of resistance is very close to zero, meaning that the resistance hardly changes at all with variations in temperature (a good property if you want to build a precision resistor out of metal wire!). The following table gives the temperature coefficients of resistance for several common metals, both pure and alloy: Positive vs. Negative TCR: A positive TCR indicates that resistance increases with rising temperature, while a negative TCR signifies a decrease in resistance with increasing temperature. It can be calculated using the formula: R_f = R_ref [1+(1⊢α(T - T_ref )] Rf = Final Resistance Rref = Initial Resistance T = Final Temperature Tref = Initial Temperature Applications: Understanding TCR is essential for designing circuits and selecting components that can maintain stable performance across different temperatures. It's also used in temperature sensing applications. Material Dependence: Different materials have different TCR values. For example, pure metals typically have positive TCRs, while some alloys have very low or even slightly negative TCRs. Practical Implications: A high TCR means a significant resistance change with temperature variations, while a low TCR indicates a more stable resistance over temperature fluctuations. 📺 Subscribe to Buda Tech for more Electrical Circuit, digital electronics, transistor logic, and Proteus simulation content. #education #electricalengineering #resistivity #electrician