Chapter 7: Temperature and Its Measurement
Introduction
Temperature is a measure of how hot or cold something is. It is an important physical quantity in daily life, experiments, and understanding weather and climate.
1. What is Temperature?
- Temperature tells us the degree of hotness or coldness of a body.
- It is measured using a thermometer.
2. Thermometers
- Mercury thermometer – uses mercury in a glass tube.
- Alcohol thermometer – uses colored alcohol in a glass tube.
- Digital thermometer – electronic measurement.
Reading a thermometer:
- Observe where the mercury or alcohol column stops.
- Record the value on the scale (°C – degrees Celsius).
3. Units of Temperature
- Celsius (°C) – widely used in India and most countries.
- Fahrenheit (°F) – used in the USA.
- Kelvin (K) – used in science for absolute temperature.
Important Points:
- Freezing point of water: 0°C (32°F)
- Boiling point of water: 100°C (212°F)
4. Measuring Temperature in Daily Life
- Body temperature – using a clinical thermometer
- Weather temperature – using a maximum-minimum thermometer
- Laboratory experiments – using mercury, alcohol, or digital thermometers
5. Key Points to Remember
- Temperature measures hotness or coldness.
- Thermometers are used to measure temperature.
- Celsius is the most common unit.
- Accurate temperature measurement is essential in science, medicine, and daily life.
Mixed-Type Questions – Temperature and Its Measurement
1. Very Short Answer (1 mark)
- What does temperature measure?
- Name one instrument used to measure temperature.
- What is the freezing point of water in Celsius?
- What is the boiling point of water in Celsius?
- Name the unit commonly used in India for temperature.
- Which thermometer is used for measuring body temperature?
- Name one electronic thermometer.
- Which thermometer uses mercury?
- Why do we measure temperature in experiments?
- What is the unit of absolute temperature?
2. Multiple Choice Questions (MCQ)
- Celsius temperature scale is denoted by:
a) °F
b) °C
c) K
d) m - The freezing point of water is:
a) 0°C
b) 100°C
c) 32°C
d) 212°C - Alcohol thermometers are preferred over mercury in:
a) Laboratories
b) Very cold regions
c) Measuring body temperature
d) Measuring hot liquids only - Digital thermometer gives reading:
a) Slowly
b) Manually
c) Electronically
d) Using mercury - Boiling point of water in Fahrenheit is:
a) 32°F
b) 212°F
c) 100°F
d) 0°F
3. Fill in the Blanks
- Temperature tells us how __________ or __________ something is.
- The unit of temperature commonly used in India is __________.
- Freezing point of water is __________°C.
- Mercury is used in __________ thermometer.
- Digital thermometer measures temperature __________.
4. True/False Type
- Celsius is used worldwide as the standard unit. (True/False)
- Boiling point of water is 0°C. (True/False)
- Alcohol thermometer can be used in very cold places. (True/False)
- Body temperature is measured using a clinical thermometer. (True/False)
- Fahrenheit scale is used in India. (True/False)
5. Short Answer Questions (2–3 marks)
- Define temperature.
- Name three types of thermometers.
- What is the unit of temperature?
- State the freezing and boiling points of water in Celsius.
- Why is accurate measurement of temperature important?
6. Long Answer Questions (4–5 marks)
- Explain how a mercury thermometer works.
- What is the difference between Celsius, Fahrenheit, and Kelvin scales?
- Describe how temperature is measured in laboratories and daily life.
- Why is body temperature measured regularly?
- Explain the importance of knowing freezing and boiling points of water.
7. Higher-Order Thinking (HOT) & Application
- A person has a temperature of 102°F. Convert it into Celsius.
- Why should alcohol thermometers be used in very cold regions instead of mercury?
- Suggest a method to measure the temperature of very hot liquids safely.
8. Passage-Based Questions
Read the passage and answer:
Temperature is a measure of how hot or cold a body is. Thermometers help in measuring it. Temperature scales like Celsius, Fahrenheit, and Kelvin are used depending on the application.
- What is temperature?
- Name three temperature scales.
- Why do we use thermometers?
- Give one application of temperature measurement in daily life.
Answer Key – Temperature and Its Measurement
1. Very Short Answer
- Hotness or coldness of a body
- Mercury thermometer, alcohol thermometer, digital thermometer, clinical thermometer
- 0°C
- 100°C
- Celsius (°C)
- Clinical thermometer
- Digital thermometer
- Mercury thermometer
- To ensure accuracy in experiments and applications
- Kelvin (K)
2. MCQ Answers
- b) °C
- a) 0°C
- b) Very cold regions
- c) Electronically
- b) 212°F
3. Fill in the Blanks
- hot, cold
- Celsius
- 0
- mercury
- electronically
4. True/False
- True
- False
- True
- True
- False
5. Short Answer
- Temperature is a measure of hotness or coldness of a body.
- Mercury thermometer, alcohol thermometer, digital thermometer
- Celsius (°C), Fahrenheit (°F), Kelvin (K)
- Freezing – 0°C; Boiling – 100°C
- Accurate measurement is important in science, medicine, and daily life.
6. Long Answer
- Mercury thermometer: Mercury expands when heated, rises in the tube, and the temperature is read on the calibrated scale.
- Celsius – 0°C (freezing), 100°C (boiling); Fahrenheit – 32°F (freezing), 212°F (boiling); Kelvin – 273 K (freezing), 373 K (boiling)
- Thermometers in laboratories, clinical thermometers for body, digital thermometers in daily life
- To detect fever or health problems early
- Freezing and boiling points are reference points for experiments, cooking, and weather studies
7. HOT & Application
- °C = (°F – 32) × 5/9 → (102 – 32) × 5/9 = 70 × 5/9 ≈ 38.9°C
- Alcohol does not freeze at very low temperatures, unlike mercury
- Use a digital or alcohol thermometer with a protective holder to measure hot liquids
8. Passage-Based
- Measure of hotness or coldness of a body
- Celsius, Fahrenheit, Kelvin
- To measure temperature accurately
- Checking body temperature, weather monitoring, experiments