Temperature Coefficient of Resistance: Calculator and Formula

This article explains the concept of the Temperature Coefficient of Resistance, providing a calculator and the formula used for its calculation.

Introduction

  • The temperature coefficient of a material describes how its physical properties change with temperature variations.

  • For instance, if a material’s resistance (R) changes by dR with a temperature change of dT, the relationship can be expressed as - dR/R = α * dT

  • Where:

    • α (alpha) represents the Temperature Coefficient, measured in units of 1/degree Kelvin (1/K) or 1/degree Celsius (1/°C).

Conductor Resistance Formula or equation

  • The resistance of a conductor generally increases with a rise in temperature.
  • Conversely, the resistance of an insulator usually decreases as temperature goes up.
  • Materials that exhibit an increase in resistance with temperature are known as PTC (Positive Temperature Coefficient) materials.
  • Materials where resistance decreases with temperature are called NTC (Negative Temperature Coefficient) materials.
  • Devices whose resistance is temperature-dependent are known as thermistors or thermal resistors. These come in two main types: PTC and NTC, as mentioned earlier.

The table below shows the temperature coefficient of resistance for some common materials:

MaterialValue of α
Copper0.0043 / °C
Nickel0.0062 / °C
Constantan0
Aluminium0.0038 / °C
Carbon-0.00048 / °C
Eureka0.00001 / °C

Temperature Coefficient of Resistance Calculator & Formula

Inputs

Outputs

The following formula is used by the calculator to compute the Temperature Coefficient of Resistance:

Temperature coefficient of resistance

This calculator determines the Temperature Coefficient of Resistance using the equation provided below.

Inputs:

  • Rref (Reference Resistance):
  • Tref (Reference Temperature):
  • R (Resistance at new temperature):
  • T (New Temperature):

Output:

  • Temperature Coefficient of Resistance, α

Example:

Let’s say:

  • Rref = 50 Ohms
  • Tref = 20 °C
  • R = 91.6 Ohms
  • T = 232 °C

Output: α = 3.92 x 10-3 (°C)-1 or 0.00392 (°C)-1