Thermistors in instrumentation – typical applications Thermistors (NTC/PTC semiconductor resistors) are commonly used in which types of devices or functions in industrial and electronic systems?

Introduction / Context:
Thermistors are temperature-sensitive resistors made from semiconductor materials. Their resistance changes predictably with temperature, making them invaluable for sensing and compensation tasks. Knowing where thermistors excel helps distinguish them from RTDs, thermocouples, and purely electrical components used for voltage or current measurement.

Given Data / Assumptions:

• NTC thermistors: resistance decreases with rising temperature.
• PTC thermistors: resistance increases with rising temperature.
• We consider mainstream industrial and electronic applications.

Concept / Approach:
Thermistors provide high sensitivity over limited ranges (often −50 °C to +150 °C for many NTC parts). They are widely used as temperature sensors (probes in HVAC, battery packs, medical devices) and as temperature-compensating elements inside circuits (bridge compensation in instrumentation amplifiers, bias stabilisation in oscillators, linearisation networks). A thermistor is not a stand-alone “voltage measuring” device; it can participate in voltage dividers or bridges, but the measurand is temperature, not voltage per se.

Step-by-Step Solution:

Verification / Alternative check:
Datasheets for NTC probes and PTC resettable devices list temperature sensing and compensation as principal uses; metrology texts classify thermistors under temperature instrumentation.

Why Other Options Are Wrong:

• Voltage measuring: A thermistor does not directly measure voltage; it forms part of a circuit measuring temperature-dependent resistance.
• None of these: Incorrect since (b) and (c) are correct.

Common Pitfalls:
Confusing a thermistor in a voltage divider with a voltmeter; the electrical signal is an intermediary to infer temperature.

Final Answer:
Both (b) and (c)