Temperature is the measure of how hot or cold something is. Everything around us – air, water, objects, and even our own body – has temperature. It affects our daily life, health, weather, and scientific experiments. Temperature depends on the movement of tiny particles (molecules) inside a substance. Faster movement = higher temperature (hot), slower movement = lower temperature (cold). To measure temperature, we use a thermometer – a special instrument that tells us the degree of heat. Types of Thermometers: 1️⃣ Mercury Thermometer – Accurate, used for high temperatures, handle with care (mercury is toxic). 2️⃣ Alcohol Thermometer – Colored alcohol rises with heat, used for very low temperatures. 3️⃣ Clinical Thermometer – Measures body temperature (35°C to 42°C). Temperature Scales: - Celsius (°C): Water freezes at 0°C, boils at 100°C. - Fahrenheit (°F): Water freezes at 32°F, boils at 212°F. - Kelvin (K): Scientific scale, absolute zero = 0 K. Why Temperature Matters: ✅ Determines the state of matter (ice → water → steam) ✅ Important in weather forecasts ✅ Used in medicine, science experiments, and industries. Conclusion: Temperature is more than just hot or cold – it is a fundamental property that influences life, nature, and science. Using thermometers and understanding temperature scales help us in health, weather, experiments, and daily life.

1. ️
🌡️Chapter 7: Temperature
and Its Measurement

2. 🔹 7.1 Hot or Cold?
• Some things are hotter and some are colder (e.g., tap water vs.
refrigerator water).
• We cannot always judge hotness or coldness correctly by touch.
• Example Activity:
Right hand in warm water, left in ice water, then both in normal water.
One hand feels warm, the other cool touch is not reliable.
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So, we need an instrument to measure how hot or cold something is.

3. 🔹 7.2 Temperature
• Temperature tells us how hot or cold a body is.
• Hotter body higher temperature.
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• Colder body lower temperature.
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• Thermometer is the device used to measure temperature.
• Two main types of thermometers:
• 1. Clinical thermometer – for measuring body temperature.
• 2. Laboratory thermometer – for measuring temperature in experiments.

4. • 🔹 7.3 Measuring Temperature
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♂️7.3.1 Clinical Thermometer
• Used to measure human body temperature.
• Earlier, mercury thermometers were used risky as mercury is toxic.
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• Now, digital thermometers are used (battery-operated, easy to read,
safe).
• Measures temperature on the Celsius scale (°C).
• Some also measure on Fahrenheit scale (°F).

5. • Normal human body temperature: 37.0 °C = 98.6 °F.
• During COVID-19, infrared thermometers were used — no contact needed.
Precautions while using a digital thermometer:
• Wash tip with soap & water before and after use.
• Keep digital part dry.
• Place under tongue or armpit (for children/elderly).
• Wait for beep read value clean again.
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• Do not hold by the tip.
Note:
• Temperature in armpit is 0.5 °C to 1 °C lower than mouth temperature.
• Normal range of body temp: 35 °C – 42 °C.

6. • 🧪 7.3.2 Laboratory Thermometer
• Used in science labs for experiments.
• Long glass tube with liquid (alcohol or mercury) inside a
bulb.
• Has a Celsius scale along the tube.
• Liquid rises or falls as temperature changes.
• Common range: –10 °C to 110 °C.
• Smallest division: usually 1 °C.

7. • Precautions while using:
1. Handle carefully (it can break easily).
2. Hold vertically, not tilted.
3. Bulb should not touch the beaker’s bottom or sides.
4. Read the temperature while the thermometer is still in water.
5. Keep your eye level with the liquid column while reading.
Note:
• Laboratory thermometers cannot measure body temperature,
because the mercury level falls immediately when taken out of the

8. • ️
🌦️7.3.3 Air Temperature
• Room thermometer or air thermometer measures air temperature.
• Found in schools, hospitals, and weather reports.
• Weather reports give maximum and minimum air temperatures.
• Air temperature changes daily and with seasons.
• Summer increases
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• Winter decreases
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9. • 🔹 7.4 Temperature Scales
• Three main scales of temperature:
• 1. Celsius (°C) – used commonly.
• 2. Fahrenheit (°F) – used earlier, still used in some countries.
• 3. Kelvin (K) – used in science; SI unit of temperature.
• Conversions:
• 37 °C = 98.6 °F
• Kelvin scale formula:
• Absolute zero: 0 K = –273.15 °C (lowest possible temperature).

10. • Writing Rules:
• Names of scales (Celsius, Fahrenheit, Kelvin) start with capital letter.
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• Units: °C, °F, K (symbols are capital).
• Write number and unit with a space (e.g., 37 °C).
• Don’t use “°” sign with Kelvin.

11. • 🔹 7.5 Normal Temperature
• Average human body temperature: 37 °C (98.6 °F).
• It can vary slightly from person to person.
• Affected by age, time of day, and activity.
• Children usually have slightly higher temperatures; older people,
lower.

12. • 🔹 7.6 Boiling and Melting Temperatures
• Temperature of ice (melting point) remains constant while melting.
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• Temperature of boiling water remains constant while boiling.
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• Boiling point at normal conditions 100 °C.
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• Melting point of ice 0 °C.
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13. THANK YOU
FOR YOUR ATTENTION