Calculate the temperature dependence of a resistor
Online calculator for calculating the temperature dependence of a resistor
The resistance of all materials is more or less dependent on the temperature. On this page, the value of a resistor at a certain temperature can be calculated using the temperature coefficient.
The temperature coefficient α gives the change in resistance for one Resistance of 1 ohm when heated by one K (Kelvin) or degree Celsius.
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Formulas of temperature dependence of a resistor
The resistance of all materials is more or less dependent on the temperature. Copper conducts better when cold. That is why copper and other metals are classed as PTC thermistors. Coal conducts better when it is warm. Therefore coal is one of the hot conductors.
The temperature drift of a resistor describes how much the resistance value of a resistor changes when the temperature changes. The temperature coefficient \(α\) indicates the change in resistance for a resistor of 1 ohm when heated by one K (Kelvin) or degree Celsius.
Example
PTC thermistors have a positive temperature coefficient and are therefore called PTC
Copper 99.9%: 0.00393
Aluminium 99.9%: 0.004
NTC thermistors have a negative temperature coefficient and are therefore called NTC
Coal: -0.00004
Constantan: -0.00008..+0.00004
There are also slightly different values for the temperature coefficients on the Internet. The value depends, among other things, on the purity of the material.
Resistance change formulas
The change in resistance is calculated:
\[\displaystyle ΔR=α · Δ ϑ · R_k\]
The resistance in the warm state is calculated:
\[\displaystyle R_w=R_k + ΔR\]
or:
\[\displaystyle R_w=R_k(1+α· Δϑ)\]
Legend
- \(\displaystyle Rk\) - Resistance at 20 °C ( Ω)
- \(\displaystyle α\) - Temperature coefficient
- \(\displaystyle Δϑ\) - Temperature change ( °C; K)
- \(\displaystyle ΔR\) - Change of resistance ( Ω)
- \(\displaystyle R_w\) - Resistance when warm (Ω)
For some metals the resistance is close to absolute zero (-273.16 ° C) at 0 ohms. We speaks here of superconductors (e.g. aluminum, lead, tin)
The formula \(\displaystyle R_w=R_k(1+α· Δϑ)\) only applies up to about \(\displaystyle Δϑ = 200K \)
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