Science Class 6 Notes Chapter 7 Curiosity

Temperature and its Measurement

Introduction:

• Temperature helps us understand how hot or cold an object or environment is.
• In this chapter, we learn about how temperature is measured, the types of thermometers used, and how they function.

Hot or Cold?

• Inference: Our sense of touch is not always reliable for determining temperature, so a thermometer is used for accurate measurement.

Temperature

• Definition: Temperature is a reliable measure of how hot or cold something is.
• Key Concept: A hotter body has a higher temperature than a colder one.
• Measuring Device: A thermometer is a device used to measure temperature.

Clinical Thermometer

• Clinical Thermometers: Used to measure human body temperature.
• Digital Clinical Thermometers: These thermometers display temperature readings digitally and are battery-operated.
• Safety: Digital thermometers are safer compared to mercury thermometers (which are being phased out due to the toxicity of mercury).
• 

Procedure for Using a Clinical Thermometer:

1. Wash the thermometer’s tip with soap and water.
2. Reset the thermometer.
3. Place it under the tongue and close your mouth.
4. Wait for a beep or light flash and then check the temperature.
5. Record the temperature and clean the thermometer again after use.

Normal Body Temperature: 37.0°C (98.6°F) is considered the average temperature of a healthy human body. However, temperatures may vary slightly among individuals due to factors like age, time of day, or activity levels.

Scales of Temperature:

• Celsius Scale: Denoted as °C, commonly used in scientific measurements.
• Fahrenheit Scale: Denoted as °F, not commonly used in scientific work but still seen in some regions.
• Kelvin Scale: Denoted as K, used in scientific studies, with no degree symbol (°) used.

Laboratory Thermometer

• Laboratory Thermometers: Used for a broader range of temperature measurements, typically from -10°C to 110°C.
• Structure: It consists of a long glass tube with a bulb filled with a liquid (usually alcohol or mercury) at the bottom.
• How it Works: The liquid in the thermometer rises when heated and falls when cooled. The temperature reading is taken where the top of the liquid column aligns with the marked Celsius scale.

Measuring Temperature with a Laboratory Thermometer:

1. Immerse the thermometer in warm water without letting the bulb touch the container’s sides or bottom.
2. Hold the thermometer vertically and read the temperature while the thermometer is still in the water.
3. Once removed from water, the liquid level begins to fall, so the reading should be taken while the thermometer is still immersed.

Air Temperature

• Air Temperature Measurement: Often measured using room thermometers or specific weather measurement instruments.
• Weather Reports: Daily maximum and minimum air temperatures are commonly shared through weather reports.

Important Temperature Ranges:

• Normal Body Temperature: Around 37.0°C (98.6°F).
• Laboratory Thermometer Range: From -10°C to 110°C.
• Human Body Temperature Range: Between 35°C and 42°C.
• Absolute Zero: The theoretical lowest temperature possible, close to -273.15°C (0 Kelvin).

Key Points to Remember:

• Temperature is a measure of how hot or cold something is.
• Thermometers are used to measure temperature accurately, as our sense of touch can be unreliable.
• Clinical Thermometers are used for human body temperatures, while Laboratory Thermometers measure a broader range of temperatures.
• Celsius, Fahrenheit, and Kelvin are the three main scales of temperature, with Celsius and Kelvin being the most used in science.