Science: Class 6 — Chapter 7: Temperature and its Measurement

7.1 Hot or Cold?

Our sense of touch is subjective and unreliable for accurately judging the hotness or coldness of an object.

7.2 Temperature and Thermometers

Temperature: A reliable, quantitative measure of the hotness or coldness of a body.
Thermometer: A device used to measure temperature.

Celsius scale: Denoted by °C. Water freezes at 0 °C and boils at 100 °C under standard conditions.
Fahrenheit scale: Denoted by °F. Historically used for clinical measurements.
Kelvin scale: Denoted by K. It is the SI unit of temperature.
Conversion Formula: Temperature in Kelvin (K) = Temperature in Celsius (°C) + 273.15.

7.3 Measuring Temperature

Clinical Thermometer: Specifically designed to measure human body temperature.
Range: 35 °C to 42 °C (human body temperature does not normally go beyond these limits).
Normal Body Temperature: 37.0 °C (equivalent to 98.6 °F).
Digital Thermometers: Modern, safe alternatives that use heat sensors instead of toxic mercury.
Infrared Thermometers: Non-contact devices that measure temperature from a distance, reducing disease transmission risk.
Precautions: Wash the tip before/after use, keep the digital display out of water, and do not hold it by the tip.

Laboratory Thermometer: Used for measuring temperatures in scientific experiments.
Range: Typically -10 °C to 110 °C.
Liquids Used: Generally red-coloured alcohol or mercury.
Correct Usage: Must be held vertically, the bulb must not touch the bottom or sides of the container, and it must be read while still immersed in the substance.

Measured using room thermometers to monitor indoor or outdoor environmental temperatures.
Weather stations track daily maximum and minimum air temperatures for forecasting.
Anna Mani (1918–2001): Known as the "Weather Woman of India", she was an pioneering Indian scientist who designed and built numerous weather-measuring instruments, promoting self-reliance in meteorology and renewable energy.