Ch 4 covers heat, temperature measurement, and how heat transfers through solids (conduction), liquids and gases (convection), and without any medium (radiation).
Temperature measures how hot or cold something is. Clinical thermometer: 35°C–42°C (has a kink to prevent mercury from flowing back). Laboratory thermometer: −10°C to 110°C. Heat flows from hotter to cooler objects.
Conduction: heat transfers through a material without molecules moving (metals are good conductors). Convection: heat transfers by actual movement of heated material (warm air/water rises). Radiation: heat transfers without any medium (how sun's heat reaches earth).
Download: https://ncert.nic.in/textbook/pdf/gesc104.pdf | Complete book: https://ncert.nic.in/textbook/pdf/gesc1ps.zip
Wool is an insulator — it traps air between its fibres. This trapped air reduces heat loss from the body, keeping us warm. The wool itself does not produce heat; it prevents body heat from escaping.
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