🔍 Key Concepts

• Resistance temperature detector (RTD) construction and sensing principle • How thermistors and thermocouples detect temperature (basic physics) • Which devices rely on change in electrical resistance versus generation of voltage or mechanical movement

💭 Think About

• Which of these devices measures temperature by a change in electrical resistance of a metal wire, and which use other effects like junction voltage or bending of metals? • Among the options, which sensor type is commonly associated with a fine platinum wire coil encased in a protective sheath? • Think about whether the device requires a reference junction (hot/cold) or simply measures resistance directly with an ohmmeter or bridge circuit.

✅ Before You Answer

• Identify which choice specifically uses platinum wire as a sensing element in many industrial applications. • Confirm which options work on resistance change in a metal versus semiconductor resistance change or thermoelectric voltage. • Eliminate any option that depends primarily on two dissimilar metals joined together or on mechanical bending rather than a coiled wire sensor.