🌡What is a thermometer?

A thermometer measures temperature—how hot or cold something is—and displays it in °C, °F, or K.

💡How it works

Every thermometer uses a material property that predictably changes with temperature, converting that change into a numeric value.

🔬Sensing principles & examples

🌡Thermal expansion: mercury/alcohol glass thermometers, bimetal dials
🔌Electrical resistance: platinum RTDs, NTC/PTC thermistors
⚡Thermoelectric effect: thermocouples (e.g., Type K)
🔴Infra-red radiation: IR “temperature guns,” thermal imagers
💻Semiconductor junction voltage: digital IC sensors in phones & PCs

📖Major types

🌡Liquid-in-glass
🧭Bimetal strip / dial
🔌RTD / thermistor
⚡Thermocouple
💻Electronic / digital
🎯Infra-red (IR)
📷Thermal imager

📊Typical uses

🩺Medical checks
💨HVAC & cold-chain monitoring
🍔Food safety
🏭Industrial processes
🔬Science & meteorology
📱Electronics thermal protection

💡Key takeaway: Thermometers translate predictable temperature-dependent changes into readable numbers, enabling everything from precise climate control to safe vaccine storage.