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Temperature and its Measurement

Chapter 7. Temperature and its Measurement

These CBSE Key Points are prepared according to the latest NCERT Curiosity textbook and CBSE competency-based pattern. They provide quick revision of important concepts, scientific terms, facts, and formulae that are frequently asked in school examinations.

CBSE Notes – Key Points

This section highlights the most important concepts of the chapter in an easy-to-revise format. Students should go through these points before examinations to strengthen their conceptual understanding and improve retention.

What is Temperature?

Temperature is the measure of the degree of hotness or coldness of a body. It helps us compare how hot or cold one object is with another. Temperature is measured using a thermometer and is expressed in different temperature scales.

Important Keywords

The following scientific terms are frequently used in this chapter and should be remembered for examinations.

Keyword	Meaning
Temperature	Measure of the hotness or coldness of a body.
Thermometer	An instrument used to measure temperature.
Clinical Thermometer	A thermometer used to measure human body temperature.
Laboratory Thermometer	A thermometer used for scientific experiments.
Celsius Scale	Commonly used temperature scale represented by °C.
Fahrenheit Scale	Temperature scale represented by °F.
Kelvin Scale	SI temperature scale represented by K.
Infrared Thermometer	A non-contact thermometer that measures temperature from a distance.
Air Temperature	The temperature of the surrounding atmosphere.
Heat Sensor	An electronic device that detects temperature changes in digital thermometers.

Important Definitions

Learning the following definitions will help students answer one-mark and competency-based questions effectively.

Term	Definition
Temperature	The degree of hotness or coldness of a body.
Thermometer	An instrument used to measure temperature accurately.
Clinical Thermometer	A thermometer specially designed to measure human body temperature.
Laboratory Thermometer	A thermometer used to measure the temperature of liquids and other substances in laboratories.
Kelvin	The SI unit of temperature.

Types of Thermometers

Different thermometers are designed for different purposes. Students should know their uses and major differences.

Thermometer	Used For	Main Feature
Clinical Thermometer	Human body	Measures body temperature accurately.
Digital Clinical Thermometer	Human body	Electronic, safe and easy to read.
Laboratory Thermometer	Experiments	Measures a wide range of temperatures.
Room Thermometer	Indoor air	Measures surrounding air temperature.
Infrared Thermometer	Body without contact	Measures temperature from a distance.

Temperature Scales

Scientists use different temperature scales depending on the purpose of measurement.

Scale	Symbol	Common Use
Celsius	°C	Daily life and school science.
Fahrenheit	°F	Used in some countries.
Kelvin	K	Scientific research and SI unit.

Important Scientific Facts

Remember these facts carefully as they are frequently asked in objective and short-answer questions.

• Temperature tells us how hot or cold an object is.
• Our sense of touch cannot accurately judge temperature.
• A thermometer provides accurate temperature measurement.
• The average normal human body temperature is 37°C (98.6°F).
• The SI unit of temperature is kelvin (K).
• Digital thermometers use electronic heat sensors.
• Mercury thermometers are being replaced because mercury is poisonous.
• Clinical thermometers are used only for measuring body temperature.
• Laboratory thermometers measure temperatures of liquids and other substances.
• Air temperature changes with weather and seasons.

Clinical Thermometer vs Laboratory Thermometer

The following comparison helps students understand the differences between the two commonly used thermometers.

Clinical Thermometer	Laboratory Thermometer
Measures body temperature.	Measures temperature of liquids and materials.
Used by doctors and at home.	Used in laboratories.
Limited temperature range.	Wide temperature range.
Suitable for medical purposes.	Suitable for scientific experiments.

Precautions While Using a Clinical Thermometer

Following these precautions ensures safe and accurate measurement of body temperature.

• Read the instruction manual before use.
• Wash the thermometer tip before and after every use.
• Keep the display unit away from water.
• Do not hold the thermometer by its tip.
• Wait for the beep before reading the temperature.

Precautions While Using a Laboratory Thermometer

These precautions help in obtaining correct temperature readings during experiments.

• Handle the thermometer carefully.
• Keep it in a vertical position.
• Do not allow the bulb to touch the container.
• Read the temperature while the thermometer is immersed.
• Take the reading at eye level.

Applications of Temperature Measurement

Temperature measurement is used in many fields of science and everyday life.

• Diagnosing fever.
• Scientific laboratory experiments.
• Weather forecasting.
• Food storage and refrigeration.
• Industrial manufacturing.
• Agriculture.
• Medical research.
• Environmental monitoring.
• Cooking and baking.
• Renewable energy studies.

Quick Revision

Revise these important points before your examination.

• Temperature is the measure of hotness or coldness.
• Thermometers are used to measure temperature.
• Clinical thermometers measure body temperature.
• Laboratory thermometers are used in experiments.
• 37°C = 98.6°F.
• Kelvin (K) is the SI unit of temperature.
• Touch cannot accurately determine temperature.
• Digital thermometers are safer than mercury thermometers.
• Laboratory thermometers should be read while immersed in the liquid.
• Temperature plays an important role in healthcare, science, industries, and weather forecasting.

Temperature and its Measurement

Chapter 7. Temperature and its Measurement

Temperature tells us how hot or cold an object is. Since our sense of touch is not always accurate, scientists use thermometers to measure temperature correctly. This chapter explains temperature, thermometers, and different temperature scales. 

Detailed Notes

Temperature

Temperature: Temperature is the measure of the degree of hotness or coldness of an object. 

Examples of Temperature

(i) Hot tea

(ii) Cold ice

(iii) Warm water

(iv) Boiling water

Importance of Temperature

(i) Helps compare hot and cold objects.

(ii) Gives accurate measurements.

(iii) Used in science and daily life.

Why Our Sense of Touch is Not Reliable

Sense of Touch: Our sense of touch cannot measure temperature accurately.

Reasons

(i) Skin adapts to different temperatures.

(ii) The same object may feel hot or cold.

(iii) It depends on previous exposure.

(iv) A thermometer gives correct readings. :contentReference[oaicite:2]{index=2}

Thermometer

Thermometer: A thermometer is an instrument used to measure temperature accurately. 

Uses of a Thermometer

(i) Measures body temperature.

(ii) Measures temperature in laboratories.

(iii) Measures air temperature.

Types of Thermometers

Types of Thermometers: Different thermometers are used for different purposes. 

Thermometer	Main Use
Clinical Thermometer	Body temperature
Digital Thermometer	Body temperature
Laboratory Thermometer	Scientific experiments
Infrared Thermometer	Non-contact measurement
Room Thermometer	Air temperature

Clinical Thermometer

Clinical Thermometer: A clinical thermometer is used to measure the temperature of the human body. 

Features of a Clinical Thermometer

(i) Measures body temperature.

(ii) Used in hospitals and homes.

(iii) Digital thermometers are commonly used.

Normal Body Temperature

(i) 37°C

(ii) 98.6°F

Advantages of Digital Thermometers

Digital Thermometer: A digital thermometer gives quick and accurate temperature readings. 

Advantages

(i) Gives fast readings.

(ii) Easy to read.

(iii) Does not contain mercury.

(iv) Safe for children.

Key Points

(i) Temperature tells how hot or cold an object is.

(ii) Our sense of touch is not always reliable.

(iii) A thermometer measures temperature accurately.

(iv) Different thermometers have different uses.

(v) The normal body temperature is 37°C or 98.6°F.

(vi) Digital thermometers are safe and easy to use.

Precautions While Using a Clinical Thermometer

Precautions: A clinical thermometer should be used carefully to get accurate readings and maintain hygiene. 

Precautions

(i) Clean the thermometer before and after use.

(ii) Read the instructions carefully.

(iii) Keep the display away from water.

(iv) Do not hold the sensing tip.

(v) Wait for the beep before reading.

Laboratory Thermometer

Laboratory Thermometer: A laboratory thermometer is used to measure the temperature of liquids and other substances during experiments. 

Uses of a Laboratory Thermometer

(i) Scientific experiments.

(ii) Measuring the temperature of liquids.

(iii) Laboratory activities.

Characteristics

(i) Has a wide temperature range.

(ii) Measures high and low temperatures.

(iii) Used only in laboratories.

Correct Method of Using a Laboratory Thermometer

Correct Method: A laboratory thermometer should be used properly to obtain accurate readings.

Steps

(i) Keep the thermometer vertical.

(ii) Immerse only the bulb in the liquid.

(iii) Do not let the bulb touch the container.

(iv) Read the temperature while it is still in the liquid.

(v) Read the scale at eye level.

Temperature Scales

Temperature Scales: Temperature is measured using different scales. 

Scale	Unit
Celsius	°C
Fahrenheit	°F
Kelvin	K

Relationship Between Temperature Scales

Temperature Scale Relationship: The same temperature can be expressed in different scales. 

Celsius	Fahrenheit	Kelvin
37°C	98.6°F	310.15 K
0°C	32°F	273.15 K

Formula

(i) Temperature (K) = Temperature (°C) + 273.15

Air Temperature

Air Temperature: Air temperature is the temperature of the surrounding atmosphere. 

Factors Affecting Air Temperature

(i) Sunlight

(ii) Clouds

(iii) Rainfall

(iv) Wind

(v) Seasons

Weather Reports

(i) Maximum temperature.

(ii) Minimum temperature.

Key Points

(i) A laboratory thermometer measures the temperature of liquids.

(ii) Always read the thermometer at eye level.

(iii) Celsius, Fahrenheit, and Kelvin are temperature scales.

(iv) Kelvin is the SI unit of temperature.

(v) Air temperature changes due to weather conditions.

(vi) Weather reports show maximum and minimum temperatures.

Applications of Temperature Measurement

Applications of Temperature Measurement: Temperature measurement is useful in healthcare, science, industries, and everyday life. :contentReference[oaicite:0]{index=0}

Uses of Temperature Measurement

(i) Diagnosing fever.

(ii) Laboratory experiments.

(iii) Weather forecasting.

(iv) Food storage and refrigeration.

(v) Industrial processes.

(vi) Agriculture.

(vii) Cooking and food processing.

(viii) Scientific research.

Importance of Accurate Temperature Measurement

Accurate Temperature Measurement: Correct temperature measurement helps us make safe and reliable decisions. :contentReference[oaicite:1]{index=1}

Importance

(i) Helps doctors diagnose illnesses.

(ii) Gives reliable scientific results.

(iii) Maintains product quality in industries.

(iv) Supports weather forecasting.

(v) Prevents incorrect observations.

Choosing the Right Thermometer

Choosing the Right Thermometer: Different thermometers are used for different purposes. 

Thermometer	Used For
Clinical Thermometer	Human body temperature
Digital Thermometer	Quick body temperature
Laboratory Thermometer	Experiments
Infrared Thermometer	Non-contact measurement
Room Thermometer	Room temperature

Quick Revision

(i) Temperature measures the hotness or coldness of an object.

(ii) Our sense of touch cannot measure temperature accurately.

(iii) A thermometer is used to measure temperature.

(iv) Clinical thermometers measure body temperature.

(v) Laboratory thermometers are used in scientific experiments.

(vi) The normal human body temperature is 37°C or 98.6°F.

(vii) Celsius, Fahrenheit, and Kelvin are temperature scales.

(viii) Kelvin (K) is the SI unit of temperature.

(ix) Weather stations measure air temperature.

(x) Accurate temperature measurement is important in healthcare, science, industries, and daily life.

Temperature and its Measurement

Chapter 7. Temperature and its Measurement

This assignment is designed according to the latest CBSE competency-based assessment pattern. It includes objective, subjective, case-based, and Higher Order Thinking Skills (HOTS) questions to help students revise the chapter thoroughly and strengthen their conceptual understanding.

Assignments – What Have You Learned?

Attempt all the following questions without referring to your textbook. This worksheet will help you improve your knowledge, application skills, and examination confidence.

Part A: Fill in the Blanks

Complete the following statements using the correct words.

1. Temperature is the measure of the __________________ of a body.
2. A __________________ is used to measure temperature.
3. The SI unit of temperature is __________________.
4. The average normal human body temperature is __________________ °C.
5. A __________________ thermometer is used to measure body temperature.
6. A laboratory thermometer usually has a range from __________________ to __________________.
7. Digital thermometers use __________________ sensors.
8. The symbol of degree Celsius is __________________.
9. Air temperature is recorded at __________________ stations.
10. Mercury thermometers are being replaced because mercury is __________________.

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Part B: True or False

Write True or False for each statement.

1. Our sense of touch can always measure temperature accurately.
2. The SI unit of temperature is kelvin.
3. Clinical thermometers are mainly used in hospitals.
4. Laboratory thermometers are suitable for measuring body temperature.
5. Digital thermometers are safer than mercury thermometers.
6. 37°C is equal to 98.6°F.
7. The bulb of a laboratory thermometer should touch the bottom of the beaker.
8. Weather reports mention maximum and minimum air temperatures.
9. Infrared thermometers measure temperature without touching the body.
10. Temperature helps us compare the hotness or coldness of objects.

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Part C: Match the Following

Match Column A with the correct answer in Column B.

Column A	Column B
1. Clinical Thermometer	(a) SI unit of temperature
2. Kelvin	(b) Measures body temperature
3. Laboratory Thermometer	(c) Weather forecasting
4. Air Temperature	(d) Scientific experiments
5. Digital Thermometer	(e) Uses electronic heat sensors

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Part D: One Word Answer

Answer each question in one word or one term.

1. Which instrument measures temperature?
2. Which thermometer measures body temperature?
3. What is the SI unit of temperature?
4. Which scale uses the symbol °F?
5. Which thermometer measures temperature without touching the body?

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Part E: Very Short Answer Questions

Answer the following questions in one or two sentences.

1. What is temperature?
2. Why is a thermometer used instead of our sense of touch?
3. State the normal body temperature of a healthy adult.
4. Name the three temperature scales.
5. What is the function of a digital thermometer?

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Part F: Short Answer Questions

Answer the following questions in about 30–50 words.

1. Differentiate between a clinical thermometer and a laboratory thermometer.
2. Write any four precautions while using a laboratory thermometer.
3. Explain why mercury thermometers are being replaced by digital thermometers.
4. Why does body temperature vary slightly among healthy people?
5. Explain why air temperature changes during different seasons.

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Part G: Long Answer Questions

Answer the following questions in detail.

1. Explain the working and uses of different types of thermometers.
2. Describe the correct procedure for measuring temperature using a laboratory thermometer.
3. Explain the importance of accurate temperature measurement in healthcare, science, and daily life.
4. Compare the Celsius, Fahrenheit, and Kelvin temperature scales.
5. Why is it important to follow safety precautions while using thermometers? Explain with suitable examples.

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Part H: Case Study Questions

Read the passage carefully and answer the questions that follow.

Riya returned home after playing outside on a hot summer afternoon. She felt tired and thought she had a fever. Her mother cleaned a digital thermometer, placed it under Riya's tongue, and waited for the beep. The thermometer showed 37°C. Her mother explained that this was the normal body temperature and advised Riya to drink water and rest for some time.

Answer the following questions:

1. Which instrument was used to measure Riya's body temperature?
2. What was the temperature reading?
3. Is 37°C considered a normal body temperature?
4. Why should the thermometer be cleaned before and after use?
5. Why should we not judge fever only by touching a person's forehead?

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Part I: Competency-Based Questions

Apply your understanding of the chapter to answer the following questions.

1. Your friend says that touching a glass of water is enough to know its exact temperature. Do you agree? Give reasons.
2. A student removes a laboratory thermometer from hot water before reading it. Will the reading be accurate? Explain.
3. Why are infrared thermometers useful in hospitals during infectious disease outbreaks?
4. How does accurate temperature measurement help weather scientists?
5. Why should different thermometers be used for different purposes?

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Part J: HOTS (Higher Order Thinking Skills)

Think carefully and answer the following questions.

1. If two objects feel equally warm to your hand, can you conclude that both have the same temperature? Explain your answer.
2. Suppose digital thermometers were not available. What safety problems might arise from using mercury thermometers?
3. Why do scientists prefer numerical temperature measurements instead of simply describing objects as hot or cold?
4. A laboratory thermometer accidentally touches the bottom of a beaker while measuring hot water. How might this affect the reading?
5. Explain why accurate temperature measurement is important in hospitals, laboratories, industries, weather forecasting, and food storage.

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Self-Assessment Checklist

Tick (✔) the statements that are true for you after completing this chapter.

• ☐ I can explain the meaning of temperature.
• ☐ I can identify different types of thermometers.
• ☐ I know the SI unit of temperature.
• ☐ I can compare Celsius, Fahrenheit, and Kelvin scales.
• ☐ I know the correct method of using a laboratory thermometer.
• ☐ I understand the precautions while using thermometers.
• ☐ I can solve competency-based and case study questions.
• ☐ I am confident about this chapter for my CBSE examination.