Temperature and Its Measurement Class 6 | Free Notes and Mind Map (Free PDF Download)

Why touch is unreliable for measuring temperature:
- Our sense of touch is subjective and influenced by previous experiences. For example:
  - If you place one hand in warm water and the other in cold water, then dip both into tap water, your perception will differ.
    - The hand from warm water will feel the tap water as cold.
    - The hand from cold water will feel the same water as warm.
- This shows that our sense of touch depends on relative differences rather than absolute temperature.
Defining temperature:
- Temperature is the scientific measure of how hot or cold any object is.
- A hotter object has a higher temperature, and temperature differences help compare the hotness or coldness of objects.
- Thermometer is the instruments used to measure temperature.

Temperature is an essential physical property that indicates the thermal energy of a substance. Key facts about temperature:

Temperature scales:
- Celsius (°C): Widely used for daily and scientific measurements.
- Fahrenheit (°F): Primarily used in the United States.
- Kelvin (K): The SI unit of temperature, used in physics and other sciences.
Normal human body temperature:
- Standard: 37.0 °C or 98.6 °F.
- Variations:
  - Can differ slightly depending on factors such as time of day, physical activity, and age.
  - A healthy human body’s temperature typically ranges from 35 °C to 42 °C.
Laboratory thermometer range:
- -10 °C to 110 °C.
- Used to measure substances with temperatures beyond the human body’s range.
Boiling and melting points:
- The boiling water temperature remains constant while boiling.
- The ice temperature stays constant during melting.

Human touch cannot measure temperature accurately due to subjective perception.
Thermometers provide an objective and precise way to measure hotness or coldness.

Clinical Thermometers
- Purpose: Measure human body temperature.
- Types:
  - Digital clinical thermometers:
    - Use heat sensors and display temperatures digitally.
    - Preferred due to ease of use and safety.
    - No risk of mercury poisoning.
  - Mercury thermometers:
    - Gradually being replaced by digital thermometers due to the toxic nature of mercury.
- Non-contact (infrared) thermometers:
  - Measure body temperature without touching the skin.
  - Useful for reducing the spread of infections.
Laboratory Thermometers
- Purpose: Measure temperature in experiments and non-human contexts.
- Structure:
  - A narrow glass tube with a bulb at one end containing alcohol (colored red for visibility) or mercury.
  - A Celsius scale marked on the tube.
Room Thermometers
- Purpose: Provide an approximate measure of room temperature.
- Commonly found in laboratories, hospitals, and homes.

Preparation:
- Wash the thermometer’s tip with soap and water or disinfect it.
- Reset the thermometer to a baseline reading.
Taking the measurement:
- Oral temperature:
  - Place the thermometer under your tongue for 1 minute.
  - Wait for the beep (digital) or observe the liquid column in a mercury thermometer.
- Armpit temperature (alternative):
  - Place the thermometer under the armpit for 1 minute.
  - Note that this reading may be 0.5 °C to 1 °C lower than oral temperature.
Post-measurement care:
- Clean the thermometer after use.
- Store it safely to avoid damage.

Preparation:
- Ensure the thermometer is clean and intact.
- Note the temperature range of the thermometer.
Taking the measurement:
- Immerse the thermometer’s bulb in the liquid to be measured.
- Ensure the bulb does not touch the sides or bottom of the container.
- Hold the thermometer vertically.
Reading the temperature:
- Observe the rise or fall of the liquid column.
- Read the scale at eye level, ensuring no parallax error occurs.
Precautions:
- Handle the thermometer carefully to prevent breakage.
- Do not use a laboratory thermometer for measuring body temperature.

Celsius Scale (°C):
- Freezing point of water: 0 °C.
- Boiling point of water: 100 °C.
- Commonly used for weather, cooking, and scientific applications.
Fahrenheit Scale (°F):
- Freezing point of water: 32 °F.
- Boiling point of water: 212 °F.
- Mainly used in the United States for daily purposes.
Kelvin Scale (K):
- Absolute zero: 0 K (equivalent to -273.15 °C).
- SI unit for scientific measurements.
- Conversion formulas:
  - Kelvin to Celsius: K – 273.15 = °C.
  - Celsius to Kelvin: °C + 273.15 = K.

Significance:
- Air temperature is a crucial weather parameter monitored worldwide.
- It helps in weather predictions and forecasts.
Measurement methods:
- Weather stations use specialized instruments to monitor air temperature.
- Weather reports provide daily maximum and minimum temperatures.
Room Thermometers:
- Measure indoor air temperature.
- Found in homes, schools, and laboratories.

Use a digital clinical thermometer for accurate results.
Follow proper steps:
- Wash the tip before and after use.
- Place the thermometer under the tongue or in the armpit.
- Wait for the beep and note the displayed reading.

Use a laboratory thermometer for experiments.
Steps to follow:
- Immerse the bulb in the liquid without touching the container’s sides or bottom.
- Observe the liquid column rise or fall.
- Note the temperature while the bulb is immersed.

Contributions:
- Known as the “Weather Woman of India.”
- Invented weather measurement instruments, reducing dependence on foreign tools.
- Her work contributed to advancements in renewable energy.
Legacy:
- Played a significant role in India’s meteorological studies and instrument development.

Temperature is a reliable measure of hotness or coldness.
Human touch is subjective and cannot accurately determine temperature. Thermometers are essential tools for precise measurement.
Different thermometers are used for various purposes:
- Clinical thermometers for the human body.
- Laboratory thermometers for experiments.
- Room thermometers for air temperature.
Air temperature plays a critical role in weather forecasting.
Scientists like Anna Mani have significantly advanced temperature measurement technologies.

This mind map contains all important topics of this chapter