Class 6 Science Chapter-10 Question Answer

1. Concept of Temperature & Sensation

• Subjectivity of Touch: Human touch cannot reliably determine the exact hotness or coldness of an object because perception is relative. 
• Definition of Temperature: Temperature is the reliable measure of the degree of hotness or coldness of an object. 
• Measuring Device: A thermometer is the scientific instrument used to measure temperature. 

2. Temperature Scales & Standards

• Celsius Scale (°C): The freezing point of water is designated as 0°C and the boiling point is 100°C. 
• Fahrenheit Scale (°F): The freezing point of water is 32°F and the boiling point is 212°F.  
• Kelvin Scale (K): The standard SI unit of temperature, designated as K.  Conversion formula: Kelvin reading = ° C + 273. 
• Fixed Points: The lower fixed point corresponds to the freezing/ice point of water, while the upper fixed point corresponds to the boiling point of water.

3. Types of Thermometers & Their Characteristics

Clinical Thermometer:

• Measurement Range: 35°C to 42°C (specifically designed for the human body). 
• Kink / Constriction (दबनाय): Features a constriction near the bulb that prevents mercury from falling automatically, allowing accurate reading after removal from the patient. 
• Normal Body Temperature: The average temperature of a healthy human body is 37°C (98.6°F). It typically does not drop below 35°C or rise above 42°C. 

Digital Clinical Thermometer:

• Replaces toxic mercury with an electronic heat sensor called a thermistor powered by a battery. 
• Displays readings directly as numeric values on an LCD screen, eliminating reading ambiguities. 

Laboratory Thermometer (आनजादसालि थार्ममिटार):

• Measurement Range: -10°C to 110°C. 
• No Kink: Because it lacks a constriction, the reading must be taken while the bulb remains completely immersed in the liquid/substance. Once removed, the mercury level drops rapidly. 
• Thermometric Liquids: Uses mercury or colored alcohol (which is red and easily visible inside the bore).

Infrared / Non-Contact Thermometer:

• Reads thermal radiation from a distance without touching the human body, widely utilized during the COVID-19 pandemic. 

Room Thermometer:

• Mounted on walls in clinics, laboratories, and weather centers to record the daily maximum and minimum atmospheric temperatures. 

4. Behavioral & Physical Observations

Constant Phase Change Temperatures:

• The temperature of water remains constant (100°C) while it is boiling. 
• The temperature of ice remains constant (0°C) while it is melting. 

Body Temperature Variations:

• Normal body temperature varies slightly based on time of day, age, and physical activity. 
• Young children generally exhibit slightly higher average temperatures, while elderly individuals often show lower temperatures. 
• Armpit (axillary) temperature readings are typically 0.5°C to 1°C lower than oral readings. 

5. Historical & Scientific Context

Early Medical Diagnostics: Before thermometers became commonplace in India, doctors primarily evaluated fevers by checking arterial pulse rates (थैरोदानि मावखांनाय हार). 

Scientist Spotlight — Anna Mani (1918–2001):

• Known as the “Weather Woman of India”. 
• Developed meteorological measuring instruments, fostering self-reliance for India in atmospheric monitoring. 
• Made foundational contributions to the measurement and utilization of wind and solar renewable energy.