Temperature and Its Measurement – Important Questions and Answers
Premium CBSE Class 6 Science revision post based on the chapter Temperature and Its Measurement. Includes hot and cold bodies, temperature, clinical thermometer, laboratory thermometer, Celsius, Fahrenheit, Kelvin scale, SI unit of temperature, correct way of measuring temperature, air temperature, weather reports, thermometer readings, case studies, HOTS, FAQs, and an interactive quiz.
Short Introduction
Temperature tells us how hot or cold a body is. We may feel hotness or coldness by touch, but our sense of touch is not always reliable. Therefore, we use a thermometer to measure temperature accurately. This chapter explains clinical thermometers, laboratory thermometers, temperature scales, precautions while using thermometers, body temperature, air temperature, and the correct method of taking temperature readings.
Chapter Overview
Hot or Cold
Our sense of touch can give an idea of hotness or coldness, but it may not always be correct.
Temperature
Temperature is a reliable measure of the hotness or coldness of a body.
Clinical Thermometer
A clinical thermometer is used to measure human body temperature.
Laboratory Thermometer
A laboratory thermometer is used to measure temperatures for laboratory purposes.
Temperature Scales
Common temperature scales are Celsius, Fahrenheit and Kelvin. The SI unit of temperature is kelvin.
Air Temperature
Weather reports mention maximum and minimum air temperatures of a place.
Important Formula and Concept Box
A hotter body has a higher temperature than a colder body.
Normal body temperature of a healthy human adult is usually taken as 37.0 °C or 98.6 °F.
Temperature in Kelvin scale = Temperature in Celsius scale + 273.15.
This helps in finding the least count of a laboratory thermometer.
Important Keywords with Meanings
| Keyword | Meaning |
|---|---|
| Temperature | A reliable measure of the hotness or coldness of a body. |
| Thermometer | A device used to measure temperature. |
| Clinical thermometer | A thermometer used to measure human body temperature. |
| Digital clinical thermometer | A battery-operated clinical thermometer that shows temperature digitally. |
| Laboratory thermometer | A thermometer used for measuring temperature in laboratory experiments. |
| Celsius scale | A temperature scale in which temperature is measured in degree Celsius. |
| Degree Celsius | Unit of temperature on Celsius scale; symbol is °C. |
| Fahrenheit scale | A temperature scale in which temperature is measured in degree Fahrenheit. |
| Degree Fahrenheit | Unit of temperature on Fahrenheit scale; symbol is °F. |
| Kelvin scale | A scientific temperature scale whose unit is kelvin. |
| Kelvin | SI unit of temperature; symbol is K. |
| SI unit of temperature | Kelvin is the SI unit of temperature. |
| Normal body temperature | Average body temperature of healthy humans, taken as 37.0 °C or 98.6 °F. |
| Infrared thermometer | A non-contact thermometer that measures temperature from a distance. |
| Non-contact thermometer | A thermometer that measures temperature without touching the body. |
| Heat sensor | A sensor used in digital thermometers to detect temperature. |
| Range of thermometer | The lowest and highest temperatures that a thermometer can measure. |
| Least count | The smallest value that a measuring instrument can measure. |
| Bulb | The lower part of a laboratory thermometer containing liquid. |
| Liquid column | The narrow column of liquid in a laboratory thermometer that rises or falls with temperature. |
| Air temperature | The temperature of air at a place. |
| Maximum temperature | The highest air temperature recorded during a day. |
| Minimum temperature | The lowest air temperature recorded during a day. |
| Weather forecast | Prediction of weather using data such as air temperature and other parameters. |
| Absolute zero | The lowest possible temperature, close to −273.15 °C or 0 K. |
Very Short Answer Questions
1. What does temperature tell us?
Answer: Temperature tells us how hot or cold a body is.
2. Can we always rely on touch to decide hotness or coldness?
Answer: No, our sense of touch is not always reliable.
3. What is temperature?
Answer: Temperature is a reliable measure of the hotness or coldness of a body.
4. Which body has higher temperature?
Answer: A hotter body has higher temperature.
5. What is a thermometer?
Answer: A thermometer is a device used to measure temperature.
6. Name two kinds of thermometers mentioned in the chapter.
Answer: Clinical thermometer and laboratory thermometer.
7. What is a clinical thermometer used for?
Answer: It is used to measure human body temperature.
8. What is a laboratory thermometer used for?
Answer: It is used for measuring temperature in laboratory activities and experiments.
9. Which scale is commonly used in clinical thermometers?
Answer: Celsius scale.
10. What is the unit of temperature on Celsius scale?
Answer: Degree Celsius.
11. What is the symbol of degree Celsius?
Answer: °C.
12. What is normal body temperature of a healthy human adult?
Answer: 37.0 °C or 98.6 °F.
13. What is the SI unit of temperature?
Answer: Kelvin.
14. What is the symbol of kelvin?
Answer: K.
15. Is the degree sign used with kelvin?
Answer: No, the degree sign is not used with kelvin.
16. What is 37.0 °C equal to on Fahrenheit scale?
Answer: 37.0 °C is equal to 98.6 °F.
17. What is the usual range of a laboratory thermometer?
Answer: Usually −10 °C to 110 °C.
18. What liquid is generally used in laboratory thermometers?
Answer: Alcohol coloured red or mercury may be used.
19. What should not touch the bottom or sides of the beaker?
Answer: The bulb of the laboratory thermometer.
20. Should a laboratory thermometer be held tilted?
Answer: No, it should be held vertically.
21. When should the reading of a laboratory thermometer be taken?
Answer: While the thermometer is still immersed in the liquid.
22. What is air temperature?
Answer: Air temperature is the temperature of air at a place.
23. Who is known as the Weather Woman of India?
Answer: Anna Mani.
24. What is absolute zero?
Answer: It is the lowest possible temperature, close to −273.15 °C or 0 K.
Short Answer Questions
1. Why can we not always rely on touch to judge temperature?
Answer: Our sense of touch can give different feelings for the same object depending on previous contact. For example, tap water may feel cool to a hand previously dipped in warm water and warm to a hand previously dipped in ice-cold water. Therefore, touch is not always reliable.
2. What is temperature?
Answer: Temperature is a reliable measure of the hotness or coldness of a body. A hotter body has higher temperature than a colder body.
3. What is the use of a thermometer?
Answer: A thermometer is used to measure temperature accurately. It helps us know how hot or cold a body is.
4. Differentiate between clinical and laboratory thermometers.
Answer: A clinical thermometer is used to measure human body temperature. A laboratory thermometer is used to measure temperatures in laboratory experiments and other purposes.
5. Why are mercury thermometers being replaced by digital thermometers?
Answer: Mercury is highly toxic and difficult to dispose of if the thermometer breaks. Digital thermometers do not pose such risk and their readings are easier to read.
6. What are infrared thermometers?
Answer: Infrared thermometers are non-contact thermometers that measure temperature without touching a person’s body. They reduce the risk of spreading disease.
7. Why is normal body temperature not exactly 37.0 °C for everyone?
Answer: 37.0 °C is the average body temperature of many healthy people. A healthy person may have a temperature slightly higher or lower because body temperature depends on age, time of day and activity level.
8. What is the usual range of human body temperature?
Answer: Human body temperature does not normally go below 35 °C or above 42 °C.
9. Why is temperature measured in the armpit slightly lower?
Answer: When temperature is measured in the armpit, it is usually about 0.5 °C to 1 °C lower than the actual body temperature.
10. Name the three common temperature scales.
Answer: The three common temperature scales are Celsius scale, Fahrenheit scale and Kelvin scale.
11. How can Celsius temperature be converted into Kelvin?
Answer: Temperature in kelvin = Temperature in degree Celsius + 273.15.
12. What is the range of the laboratory thermometer shown in the chapter?
Answer: The range of the laboratory thermometer shown in the chapter is from −10 °C to 110 °C.
13. How do we find the smallest value a thermometer can read?
Answer: Divide the temperature difference between two bigger marks by the number of smaller divisions between them.
14. Why should the thermometer reading be taken while the bulb is immersed in water?
Answer: As soon as the thermometer is taken out of water, the liquid column starts falling. Therefore, the reading must be taken while the thermometer is still immersed.
15. Why is air temperature important?
Answer: Air temperature is an important weather parameter. It is monitored at weather stations and used along with other data to prepare weather forecasts.
Long Answer Questions
1. Explain why our sense of touch is not reliable for measuring temperature.
Answer: Our sense of touch can be misleading. In the activity with three containers, one hand is first placed in warm water and the other in ice-cold water. When both hands are then placed in tap water, the hand that was in warm water feels the tap water as cool, while the hand that was in ice-cold water feels the same tap water as warm. This shows that touch depends on previous sensation and cannot measure temperature accurately. Therefore, a thermometer is needed.
2. Explain clinical thermometer and its use.
Answer: A clinical thermometer is used to measure human body temperature. Modern clinical thermometers are mostly digital and run on batteries. They show the temperature on a digital display. They measure temperature using heat sensors when placed in contact with the body. The commonly used scale is Celsius scale and the unit is degree Celsius, written as °C.
3. Write precautions while using a digital clinical thermometer.
Answer: The following precautions should be taken:
- Use the thermometer after reading the instruction manual.
- Wash hands before use.
- Wash the tip of the thermometer with soap and water before and after use.
- Keep the digital display portion away from water while washing.
- Do not hold the thermometer by the tip.
- Wait for the beep sound or flashing light before reading the temperature.
4. Explain normal body temperature and factors affecting it.
Answer: Normal temperature of a healthy human adult is taken as 37.0 °C or 98.6 °F. However, every healthy person may not have exactly 37.0 °C. It is an average value based on many healthy people. Body temperature may vary slightly due to age, time of the day and activity level. Small children may have slightly higher body temperature, while old people may have slightly lower temperature than young adults.
5. Explain Celsius, Fahrenheit and Kelvin scales.
Answer: The three common temperature scales are Celsius, Fahrenheit and Kelvin. On the Celsius scale, temperature is measured in degree Celsius and written as °C. On the Fahrenheit scale, temperature is measured in degree Fahrenheit and written as °F. A normal body temperature of 37.0 °C is equal to 98.6 °F. On the Kelvin scale, temperature is measured in kelvin and written as K. Kelvin is the SI unit of temperature. The degree sign is not used with K.
6. Write a note on laboratory thermometer.
Answer: A laboratory thermometer is used to measure temperature in laboratory experiments. It consists of a long, narrow and uniform glass tube sealed at both ends. At one end, there is a bulb containing a liquid such as alcohol coloured red or mercury. A narrow liquid column rises or falls with change in temperature. A Celsius scale is marked along the tube. The temperature reading is taken where the top of the liquid column matches the scale marking.
7. Explain how to find the range and least count of a laboratory thermometer.
Answer: The range of a thermometer is found by observing the lowest and highest temperature markings on the thermometer. For example, the laboratory thermometer shown in the chapter has a range from −10 °C to 110 °C. To find the least count, note the temperature difference between two bigger marks and divide it by the number of smaller divisions between them. If there are 10 divisions between 0 °C and 10 °C, then one division measures 1 °C. Therefore, the least count is 1 °C.
8. Explain the correct way of measuring temperature using a laboratory thermometer.
Answer: The correct method is:
- Take the liquid in a beaker.
- Dip the thermometer so that the bulb is immersed in the liquid.
- The bulb should not touch the bottom or sides of the beaker.
- Hold the thermometer vertically; do not tilt it.
- Wait until the liquid column stops rising or falling.
- Read the temperature while the thermometer is still immersed in the liquid.
- Keep the eye directly in line with the top level of the liquid column.
9. Why is a laboratory thermometer not used for measuring body temperature?
Answer: A laboratory thermometer is not suitable for measuring body temperature because it is generally longer and fragile, and its reading must be taken while it is still in contact with the body. Once removed, the liquid column may fall, giving a wrong reading. A clinical thermometer is specially designed to measure human body temperature safely and conveniently.
10. Explain air temperature and its importance in weather forecasting.
Answer: Air temperature is the temperature of air at a place. Weather reports mention maximum and minimum air temperatures for the day. These temperatures vary daily because weather depends on several factors. As summer approaches, temperature usually rises, and in winter, it falls. Air temperature is measured at weather stations and used with other weather data to make weather forecasts. Anna Mani, known as the Weather Woman of India, developed many weather measurement instruments.
Case-Study Based Questions
Case Study 1: Hot and Cold Water
A student dips the right hand in warm water and the left hand in ice-cold water for 1–2 minutes. Then both hands are placed in tap water. The right hand feels tap water as cool, while the left hand feels it as warm.
Q1. What does this activity show?
Answer: It shows that our sense of touch is not always reliable for judging temperature.
Q2. What should be used for accurate temperature measurement?
Answer: A thermometer should be used.
Q3. Define temperature.
Answer: Temperature is a reliable measure of the hotness or coldness of a body.
Case Study 2: Measuring Body Temperature
Phiban washes the tip of a digital clinical thermometer, resets it, places it under Lambok’s tongue, waits for the beep and reads the display.
Q1. Which thermometer did Phiban use?
Answer: A digital clinical thermometer.
Q2. Why did she wash the tip before and after use?
Answer: To maintain cleanliness and reduce the chance of spreading infection.
Q3. What is normal body temperature usually taken as?
Answer: 37.0 °C or 98.6 °F.
Case Study 3: Laboratory Thermometer
A laboratory thermometer has markings from −10 °C to 110 °C. Between 0 °C and 10 °C there are 10 equal divisions.
Q1. What is the range of this thermometer?
Answer: −10 °C to 110 °C.
Q2. What is the value of one small division?
Answer: 10 °C ÷ 10 = 1 °C.
Q3. What is another name for the smallest value it can measure?
Answer: Least count.
Case Study 4: Wrong Reading
A student measures warm water using a laboratory thermometer. The bulb touches the bottom of the beaker and the thermometer is tilted.
Q1. Is this the correct method?
Answer: No, this is not the correct method.
Q2. What should be corrected?
Answer: The bulb should not touch the bottom or sides, and the thermometer should be held vertically.
Q3. Where should the eye be while taking the reading?
Answer: The eye should be directly in line with the top level of the liquid column.
Case Study 5: Weather Report
A city records maximum and minimum air temperatures for 10 days. The temperatures vary each day.
Q1. Why do air temperatures vary every day?
Answer: Because weather depends on several factors.
Q2. What happens to temperature as summer approaches?
Answer: Temperature usually rises.
Q3. How is air temperature useful?
Answer: It is an important weather parameter used for weather forecasts.
Assertion-Reason Questions
Choose the correct option:
A. Both Assertion and Reason are true and Reason is the correct explanation.
B. Both Assertion and Reason are true but Reason is not the correct explanation.
C. Assertion is true but Reason is false.
D. Assertion is false but Reason is true.
1. Assertion: Touch is not always reliable for judging hotness or coldness. Reason: The same tap water can feel warm to one hand and cool to the other.
Answer: A
2. Assertion: Temperature is a reliable measure of hotness or coldness. Reason: A hotter body has a higher temperature.
Answer: A
3. Assertion: A thermometer measures temperature. Reason: A barometer measures body temperature.
Answer: C
4. Assertion: Clinical thermometers are used to measure human body temperature. Reason: Laboratory thermometers are used for many other purposes.
Answer: B
5. Assertion: Mercury thermometers are being replaced by digital thermometers. Reason: Mercury is toxic and difficult to dispose of safely.
Answer: A
6. Assertion: Normal body temperature is exactly 37.0 °C for every healthy person. Reason: Body temperature may vary with age, time and activity level.
Answer: D
7. Assertion: Kelvin is the SI unit of temperature. Reason: The symbol of kelvin is K.
Answer: B
8. Assertion: A clinical thermometer can be used to measure boiling water. Reason: Boiling water temperature is outside the range of a clinical thermometer.
Answer: D
9. Assertion: The bulb of a laboratory thermometer should not touch the bottom of the beaker. Reason: It can give an incorrect temperature reading.
Answer: A
10. Assertion: Air temperature is useful in weather forecasting. Reason: Air temperature is an important weather parameter.
Answer: A
Competency-Based and Critical Thinking / HOTS Questions
1. Why did Lambok’s sister use a thermometer instead of only touching his forehead?
Answer: Touch can only give a rough idea and may be misleading. A thermometer gives a reliable measurement of body temperature and confirms whether a person has fever.
2. Why is wrong measurement worse than no measurement?
Answer: Wrong measurement may lead to wrong conclusions and actions. For example, an incorrect body temperature reading may wrongly suggest fever or no fever.
3. Why was a non-contact thermometer useful during the COVID-19 pandemic?
Answer: It could measure temperature from a distance without touching the person, reducing the risk of spreading infection.
4. A child’s temperature is 36.8 °C. Is it necessarily abnormal?
Answer: No. Normal body temperature is an average value and may vary slightly from person to person. 36.8 °C can be normal for a healthy person.
5. Why is a laboratory thermometer not ideal for checking fever at home?
Answer: It is fragile, must be read while in contact with the body, and is not designed for safe and convenient body temperature measurement. A clinical thermometer is better.
6. A thermometer has 50 divisions between 0 °C and 100 °C. What is the value of one division?
Answer: One division = 100 °C ÷ 50 = 2 °C.
7. Which scale is Komal likely using if she says she has fever of 101 degrees?
Answer: She is likely using the Fahrenheit scale because 101 °F indicates fever, while 101 °C is far beyond human body temperature and impossible for a living person.
8. Why can boiling water in Shillong show a temperature close to 98 °C instead of 100 °C?
Answer: Boiling temperature can vary with atmospheric pressure. Shillong is at a higher altitude, where water may boil at a temperature lower than 100 °C.
9. Why should the eye be directly in line with the liquid column while reading a thermometer?
Answer: This prevents reading error due to viewing from an angle and gives a more accurate temperature reading.
10. Why does the liquid column in a laboratory thermometer fall after it is removed from warm water?
Answer: After removal, the thermometer starts losing heat to the surrounding air. The liquid column falls as the temperature of the thermometer decreases.
Diagram-Based Questions
Diagram 1: Sense of Touch Activity
A
Warm water
B
Tap water
C
Ice-cold water
Question: Why does the same tap water feel different to two hands?
Answer: Because the hands were previously in water of different temperatures, so touch gives a misleading feeling.
Diagram 2: Temperature Scales
Question: Convert 37.0 °C into kelvin.
Answer: 37.0 + 273.15 = 310.15 K.
Diagram 3: Laboratory Thermometer Parts
Question: Which part of the thermometer should be immersed in water?
Answer: The bulb should be immersed in water.
Diagram 4: Correct Reading of Laboratory Thermometer
Correct
Thermometer vertical
Bulb not touching beaker
Eye in line with liquid column
Incorrect
Thermometer tilted
Bulb touching beaker
Eye above or below mark
Question: When should the temperature be read?
Answer: While the thermometer is still immersed in the liquid.
Diagram 5: Daily Air Temperature Record
Question: Why do maximum and minimum temperatures vary daily?
Answer: Because weather depends on several factors and changes from day to day.
Quick Revision Box
- Temperature tells us how hot or cold a body is.
- Touch is not always reliable for judging hotness or coldness.
- A thermometer is used to measure temperature.
- A hotter body has a higher temperature.
- Clinical thermometer measures human body temperature.
- Laboratory thermometer is used for laboratory purposes.
- Digital clinical thermometers use heat sensors.
- Mercury is toxic, so mercury thermometers are being replaced.
- Infrared thermometers measure temperature without touching the body.
- Temperature on Celsius scale is measured in degree Celsius.
- Symbol of degree Celsius is °C.
- Normal body temperature is taken as 37.0 °C or 98.6 °F.
- Body temperature can vary with age, time and activity level.
- Human body temperature normally does not go below 35 °C or above 42 °C.
- Fahrenheit scale uses degree Fahrenheit, symbol °F.
- Kelvin scale uses kelvin, symbol K.
- SI unit of temperature is kelvin.
- Temperature in K = Temperature in °C + 273.15.
- Laboratory thermometer usually ranges from −10 °C to 110 °C.
- The bulb should not touch the bottom or sides of the beaker.
- Laboratory thermometer should be held vertically.
- Reading must be taken while the thermometer is immersed.
- Eye should be in line with the top level of liquid column.
- Air temperature is important for weather forecasting.
- Anna Mani is known as the Weather Woman of India.
Important Exam Tips
Interactive Quiz
Choose the correct answer and click submit.
Frequently Asked Questions
1. What is temperature?
Temperature is a reliable measure of the hotness or coldness of a body.
2. Why can touch not always judge temperature correctly?
Touch can be affected by previous sensations, so the same water may feel warm to one hand and cool to another.
3. What is a thermometer?
A thermometer is a device used to measure temperature.
4. What is a clinical thermometer?
A clinical thermometer is used to measure human body temperature.
5. What is normal body temperature?
Normal body temperature of a healthy human adult is taken as 37.0 °C or 98.6 °F.
6. What is the SI unit of temperature?
The SI unit of temperature is kelvin, written as K.
7. What is the usual range of a laboratory thermometer?
A laboratory thermometer usually has a range from −10 °C to 110 °C.
8. Why should we not use a laboratory thermometer for body temperature?
It is fragile and must be read while still in contact with the body, so it is not suitable for checking fever at home.
9. What is an infrared thermometer?
An infrared thermometer is a non-contact thermometer that measures temperature without touching the body.
10. Who was Anna Mani?
Anna Mani was an Indian scientist known as the Weather Woman of India for her work on weather measurement instruments.
Final Conclusion
The chapter Temperature and Its Measurement teaches that temperature is the scientific way to measure hotness or coldness. Since touch can be misleading, thermometers are used for accurate measurement. Clinical thermometers measure body temperature, while laboratory thermometers are used for experiments. Students must know temperature scales, correct units, thermometer precautions, proper reading method and the importance of air temperature in weather forecasting.
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