Class 6 Science Chapter 7 Temperature and its Measurement Notes & Summary in English for CBSE students
CBSE Class 6 Science Chapter 7 Notes & Summary in English for “Temperature and its Measurement” (based on NCERT textbook Curiosity ).
Chapter 7 – Temperature and its Measurement Complete Notes
(Complete Notes + Concept-wise Explanation + Summary CBSE Class 6 Science – Curiosity Book)
1. Introduction to Temperature
Temperature tells us how hot or cold a body is.
We cannot always depend on touch to judge hotness or coldness.
For example, warm water may feel cold to one hand and warm to another depending on their initial condition (Activity 7.1).
Therefore, we need a reliable measurement → Temperature.
Definition:
Temperature is a measure of the degree of hotness or coldness of a body.
Instrument used: Thermometer.
2. Hot and Cold – Why Touch Is Not Reliable
Activity 7.1 shows that:
- If you keep one hand in warm water and the other in cold water,
- And then put both hands in normal water,
- Both hands will feel different sensations.
Inference:
Sense of touch is not reliable for deciding temperature.
Thus, temperature must be measured using a thermometer.
3. What Is Temperature?
Temperature:
- Indicates relative hotness.
- Higher temperature → hotter body.
- Lower temperature → colder body.
Unit of temperature:
- Degree Celsius (°C)
- Degree Fahrenheit (°F)
- Kelvin (K)
SI unit of temperature: Kelvin (K)
4. Thermometers – Types and Uses
Thermometers are devices used to measure temperature.
There are three main types discussed in this chapter:
- Clinical Thermometer (for body temperature)
- Laboratory Thermometer (for experiments)
- Room Thermometer (air temperature)
5. Clinical Thermometer
Used to measure human body temperature.
Earlier:
- Mercury thermometers were used.
- Mercury is toxic → gradually replaced by digital thermometers.
Now:
- Digital thermometers are used.
- They show reading on a display.
- They use heat sensors instead of mercury.
Normal Body Temperature:
- 37°C OR 98.6°F
Range of a clinical thermometer:
- Around 35°C to 42°C
(because human body temperature does not go beyond this range)
Precautions while using a clinical thermometer:
- Wash the tip with soap and water before and after use.
- Do not hold the thermometer by the tip.
- Keep the digital display away from water.
- Keep it under the tongue or in the armpit (armpit reading is 0.5°C–1°C lower).
Special thermometers used during COVID-19:
Non-contact infrared thermometers.
6. Celsius, Fahrenheit and Kelvin Scales
Different scales used to measure temperature:
Celsius Scale (°C)
- Most commonly used in science.
- 0°C = freezing point of water
- 100°C = boiling point of water
Fahrenheit Scale (°F)
- Used earlier and still used for body temperature in some countries.
- 98.6°F is equal to 37°C.
Kelvin Scale (K)
- Used in scientific experiments.
- Kelvin = Celsius + 273.15
- 0 K = absolute zero (lowest possible temperature)
7. Measuring Body Temperature with a Digital Thermometer
Steps:
- Wash hands and the thermometer tip.
- Reset the thermometer.
- Place under the tongue and close mouth.
- Wait for beep/light.
- Read display.
- Clean and dry the tip.
Factors affecting body temperature:
- Age
- Time of day
- Activity level
Body temperature normally stays between 35°C and 42°C.
8. Laboratory Thermometer
Used to measure temperatures of:
- liquids
- experiments
- objects other than human body
Structure:
- Long, uniform glass tube
- Bulb at one end filled with mercury or coloured alcohol
- Shows reading by rising of liquid column
Range of laboratory thermometer:
–10°C to 110°C (typical)
Finding Smallest Division:
- Check difference between two big marks
- Count number of small divisions
- Divide to get value of one small division (often 1°C)
9. Correct Way of Using a Laboratory Thermometer
Rules:
- Bulb must not touch bottom/sides of beaker.
- Hold thermometer vertically.
- Read while bulb is still in water.
- Eye level must be in line with top of liquid column.
Important:
- Once taken out, reading begins to fall → read while inside.
10. Can We Use a Laboratory Thermometer to Measure Body Temperature?
No, because:
- Its range is much larger.
- Body temperature falls quickly if thermometer is removed.
- It cannot be used in the mouth safely.
11. Temperature of Boiling Water and Ice
Temperature of:
- Boiling water remains constant while it is boiling.
- Ice remains at constant temperature while melting.
Slight variations in readings occur because:
- Students may not follow precautions.
- Eye level may not be correct.
- Bulb may touch sides or bottom.
12. Air Temperature
Measured using:
- Room thermometer
- Thermometers kept on walls (Fig. 7.5)
Weather reports mention:
- Maximum temperature of the day
- Minimum temperature of the day
Temperature varies daily due to:
- Weather conditions
- Seasons
13. Daily Temperature Record (Weather Activity)
Students record:
- Max and Min temperature for 10 days
- Compare variations
- Understand why values change each day
14. About Scientist – Anna Mani
Anna Mani (1918–2001):
- Known as “Weather Woman of India”
- Built many weather instruments
- Reduced India’s dependence on other countries
- Promoted wind and solar energy research
- Helped India become a leader in renewable energy
Important Keywords (Definitions)
Temperature: measure of heat or cold.
Thermometer: instrument to measure temperature.
Celsius scale: temperature scale using °C.
Fahrenheit scale: uses °F.
Kelvin scale: SI unit scale for precise scientific temperatures.
Clinical thermometer: used for measuring body temperature.
Laboratory thermometer: used in experiments.
Air temperature: temperature of surrounding air.
Range: lowest to highest reading of a thermometer.
Smallest division: minimum value the thermometer can measure.
Predict, Observe, Record, Compare: steps in scientific method.
Summary (Key Points)
The temperature of a body tells how hot or cold it is.
Three temperature scales: Celsius, Fahrenheit and Kelvin.
SI unit of temperature: kelvin (K).
Normal body temperature: 37°C or 98.6°F.
Digital clinical thermometers are safe and easy to use.
Mercury thermometers are being phased out.
Laboratory thermometers have a wide range (–10°C to 110°C).
Temperature must be read when the thermometer is still in the substance.
Room thermometers measure air temperature.
Weather reports give maximum and minimum daily temperatures.