Which instrument is used to measure temperature?

• A. Barometer
• B. Ammeter
• C. Thermometer
• D. Voltmeter

Answer: (C)

The instrument used to measure temperature is indeed a thermometer. This device specifically responds to changes in temperature and provides a reading based on the expansion or contraction of a liquid (commonly mercury or alcohol) or by utilizing electronic sensors in digital thermometers. The principle behind its operation is based on the physical properties of materials that change with temperature, allowing for accurate measurement of how hot or cold an object or environment is.

In contrast, the barometer is utilized to measure atmospheric pressure, while an ammeter measures electric current in a circuit. A voltmeter, on the other hand, is designed to measure the electrical potential difference (voltage) across two points in a circuit. Each of these instruments has a specific purpose related to different physical properties, which distinguishes the thermometer's function as solely related to temperature measurement.