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).

• 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:

Temperature Coefficient of Resistance Calculator

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^

Temperature Coefficient of Resistance Formula

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