Thermistor Characteristics Apparatus

The Thermistor Characteristics Apparatus is a laboratory setup used to study how the resistance of a thermistor changes with temperature, providing insights into its negative temperature coefficient (NTC) or positive temperature coefficient (PTC) behavior.

Apparatus Description

Components:

The apparatus generally includes a thermistor (commonly NTC type), a regulated DC power supply (0–10 V), two digital or analog meters for voltage and current measurement, and a heating arrangement such as an electrically heated oven or water bath with a glass/mercury thermometer to control and monitor temperature.

Principle and Working

The thermistor is a temperature-sensitive resistor, whose resistance changes significantly with temperature - an NTC thermistor’s resistance decreases as temperature increases, while a PTC thermistor’s resistance increases.

The thermistor is connected in a circuit so that its resistance can be monitored as the temperature is systematically changed using the heating arrangement.

Experimental Procedure

The thermistor is placed inside the oven or bath, and the circuit is completed for resistance measurement.

The temperature is increased in steps, and for each temperature setting, the corresponding resistance of the thermistor is recorded using the voltmeter-ammeter readings (Ohm’s law).

A graph of resistance versus temperature is plotted, which typically shows the characteristic exponential drop for NTC thermistors.

Applications

This experiment demonstrates the rapid resistance-temperature response of thermistors, foundational to their use in temperature measurement, compensation, and control systems.