What happens to the resistance of an RTD as its temperature increases?

The resistance of a Resistance Temperature Detector (RTD) increases as its temperature rises. This characteristic is due to the physical properties of the materials used in RTDs, which are typically made of pure metals such as platinum. As the temperature of the metal increases, the atoms vibrate more vigorously, leading to more frequent collisions of the electrons flowing through the material. This increased atomic activity results in higher resistance.

This behavior is essential in temperature measurement applications, as it allows for accurate temperature readings based on the change in resistance. The relationship between temperature and resistance in an RTD is typically linear over a certain range, especially for platinum, which is why RTDs are favored for precise temperature measurement in various industrial and scientific applications.