Which instrument measures humidity?

• A. Thermometer
• B. Barometer
• C. Hygrometer
• D. Anemometer

Answer: (C)

Humidity is the amount of water vapor in the air, and a hygrometer is the instrument used to measure it. Hygrometers can be mechanical, using materials like human hair that change length with humidity, or electronic, using sensors that detect moisture-related changes in electrical properties. They provide relative humidity as a percentage, often along with temperature. The other tools measure different things: a thermometer tracks temperature, a barometer measures air pressure, and an anemometer gauges wind speed. So when you need to know how moist the air is, a hygrometer is the right instrument because it’s specifically designed to sense and quantify water vapor in the atmosphere.