NCERT Solutions for Class 7th Science Chapter 7 Heat Transfer in Nature
Updated on 2026-09-19
About this chapter
Heat travels from a hotter place to a colder place in three ways — conduction , convection and radiation . Pema and Palden meet all three in one evening: the metal pan on the fire, the smoke rising from the burning wood, and the warmth they feel sitting around the fireplace. In conduction , heat passes from the hotter part of an object to its colder part. A heated particle passes heat on to its neighbour, and so on, but the particles themselves do not move from their positions . This is how heat travels in solids. Materials that let heat pass through them easily — metals such as aluminium, iron and steel — are good conductors of heat . Wood, glass, clay, porcelain, plastic and air are poor conductors (insulators) . Woollen clothes, two thin blankets and hollow bricks all work by trapping a
- Chapter opener
- .1 Conduction of Heat
- .1 Conduction of Heat / 7.2 Convection
- .2 Convection
- .2.1 Land and Sea Breeze
- .3 Radiation
- .4 Water Cycle
- .4.1 Seepage of water beneath the Earth
- Chapter exercises
- Chapter projects
Quick revision
| Term | What it means | Example from the chapter | Point to remember |
|---|---|---|---|
| Conduction | Transfer of heat from the hotter part of an object to its colder part | Pins I, II, III, IV falling one after another from a heated metal strip (Activity 7.1) | Particles pass heat on but do not leave their positions |
| Good conductor of heat | A material that allows heat to pass through it easily | Aluminium, iron, steel — used for cooking utensils | All metals are good conductors of heat |
| Poor conductor (insulator) | A material that does not allow heat to pass through it easily | Wood, glass, clay and porcelain cups, plastic, air | Air is one of the best insulators — wool and hollow bricks use it |
| Convection | Transfer of heat by the actual movement of particles of a liquid or a gas | The coloured streak rising in the middle and coming down at the sides (Activity 7.3) | Works only in liquids and gases, never in solids |
| Sea breeze | Movement of cooler air from the sea towards the land | Blows during the day, when land is warmer than the sea (Fig. 7.7a) | Windows of coastal houses face the sea to catch it |
| Land breeze | Movement of cooler air from the land towards the sea | Blows at night, when the sea is warmer than the land (Fig. 7.7b) | The wind direction reverses between day and night |
| Radiation | Transfer of heat that does not require any medium | Heat of the Sun reaching the Earth; warmth felt around a fireplace | All objects radiate heat to their surroundings |
| Water cycle | The continuous upward movement of water as vapour and downward movement through precipitation | Evaporation, transpiration, condensation and precipitation (Fig. 7.9) | It redistributes water and conserves the Earth's total water |
| Evaporation | Change of water into water vapour | Wet clothes drying faster on a sunny day | The Sun's heat makes evaporation faster |
| Transpiration | Loss of water as vapour from trees and plants | Shown by the arrow rising from the tree in Fig. 7.9 | It adds to the water vapour in the air along with evaporation |
| Precipitation | Water falling from clouds as rain, snow or hail | Clouds bring rain, snow and hail | It is the downward half of the water cycle |
| Infiltration | The seeping of surface water through soil and rocks | Water passing fastest through gravel and slowest through clay (Activity 7.5) | Wider, open and interconnected spaces allow faster infiltration |
| Groundwater | Water stored in the pore spaces of sediments and openings in rocks beneath the surface | The water drawn from wells and handpumps | It is not unlimited — it is getting depleted |
| Aquifer | An underground layer of sediments and rocks that stores water in pore spaces | Fig. 7.12 — a well drawing water from an aquifer | May lie a few metres to hundreds of metres below the ground |
Exercises
- Chapter opener — In-text Questions Page 89–90
- .1 Conduction of Heat — Activity 7.1: Let us experiment Page 907
- .1 Conduction of Heat — In-text Questions Page 917
- .1 Conduction of Heat / 7.2 Convection — In-text Questions Page 927
- .2 Convection — Activity 7.2: Let us investigate Page 92–937
- .2 Convection — In-text Questions Page 937
- .2 Convection — Activity 7.3: Let us find out Page 93–947
- .2 Convection — In-text Question Page 947
- .2.1 Land and Sea Breeze — Activity 7.4: Let us investigate Page 94–957
- .2.1 Land and Sea Breeze — In-text Question Page 957
- .3 Radiation — In-text Questions Page 967
- .3 Radiation — Dive Deeper Page 967
- .4 Water Cycle — Know a Scientist Page 997
- .4.1 Seepage of water beneath the Earth — In-text Question Page 997
- .4.1 Seepage of water beneath the Earth — Activity 7.5: Let us investigate Page 997
- .4.1 Seepage of water beneath the Earth — In-text Questions Page 1007
- .4.1 Seepage of water beneath the Earth — Science and Society Page 1017
- Chapter exercises — Let Us Enhance Our Learning Page 102–104
- Chapter projects — Exploratory Projects Page 104