What occurs to the resistance of an RTD sensor as it is heated?

An RTD (Resistance Temperature Detector) sensor is designed to measure temperature through its resistance changes that are directly correlated to temperature variations. As the temperature rises, the atoms within the conductive material of the RTD vibrate more vigorously, which disrupts the flow of electric current. This increased atomic movement leads to a higher resistance value.

The primary working principle of an RTD relies on the characteristic of metals—where most metals experience an increase in resistance with an increase in temperature. Therefore, as the RTD sensor is heated, the resistance increases in a predictable and nearly linear fashion, allowing for accurate temperature measurements across a range of values. This makes option C the correct choice.