🔍 Key Concepts

• Thermal volumetric expansion means a liquid’s volume increases as temperature increases • A direct reading thermometer lets you read temperature straight from a scale without any electrical conversion • Which of these devices typically has a linear scale printed alongside or around the sensing element

💭 Think About

• For each option, picture its physical form: which one usually has a sealed tube partially filled with liquid and a scale beside it? • Consider which choices commonly produce an electrical signal versus a simple visible movement of fluid or metal you can read directly. • Ask yourself: which device depends specifically on a liquid changing volume rather than metal flexing or voltage being generated?

✅ Before You Answer

• Verify which devices (from the choices) are non‑electrical, purely mechanical indicators. • Check which one is specifically described in textbooks as using a liquid in a transparent tube to show temperature. • Eliminate any devices whose main sensing principle is metal deformation or generation of an electrical potential, not liquid expansion.