When the temperature of a positive temperature coefficient (PTC) thermistor increases, how does its resistance behave?

A positive temperature coefficient (PTC) thermistor is a type of resistor whose resistance increases with an increase in temperature. This characteristic is due to the material properties of the thermistor, which causes it to behave as a resistive device that becomes less conductive when it is heated.

As the temperature rises, the increased thermal energy causes more charge carriers to move, but the material's structure leads to increased resistance in the flow of electric current. Therefore, when the temperature of a PTC thermistor increases, its resistance also increases. This behavior is utilized in various applications, such as overcurrent protection and temperature sensing, where it is crucial to monitor changes in resistance relative to temperature fluctuations.

This understanding is critical for HVAC professionals who need to work with these components in systems to ensure proper functionality and safety.