भूगोल Geography

Quick summary

Because the Earth rotates from west to east, places on different longitudes have different times for sunrise, noon and sunset. This chapter explains local time based on the sun's position, how to calculate time differences using longitude, why standard time is needed, the Indian Standard Time, time zones and Greenwich Mean Time.

Key points

• The Earth completes one rotation (360°) in about 24 hours, from west to east. So the sun appears to move from east to west.
• Shadows are longest in the morning and evening and shortest at noon.
• The time of a place decided by the position of the sun in the sky (noon when the sun is highest) is its local time (स्थानिक वेळ). All places on the same longitude have the same local time.
• The Earth turns 15° in one hour, i.e. 1° in 4 minutes. So local time changes by 4 minutes for every degree of longitude.
• Places east of a longitude are ahead in time; places west are behind.
• Using local times within a large country would cause confusion, so the local time of a longitude passing through the middle of the country is taken as the standard time for the whole country.
• Indian Standard Time (IST) is based on the 82°30' E longitude passing through Mirzapur near Prayagraj (Allahabad), Uttar Pradesh.
• Countries with a large east–west extent (e.g. Russia, USA, Canada, Australia) have more than one standard time zone.
• For international coordination, the local time at Greenwich (0°, Prime Meridian), called Greenwich Mean Time (GMT), is the universal standard time.
• IST is 5 hours 30 minutes ahead of GMT. When it is 5 pm at Greenwich, it is 10:30 pm in India.
• Old time-measuring devices: ghatikapatra (water bowl), sand timer, sundial. Maharaja Sawai Jaisingh II built Jantar-Mantar observatories.

Important terms

• Local time – time of a place based on the sun's position (noon when the sun is overhead).
• Standard time – one common time for a country, based on a central longitude.
• Prime Meridian – 0° longitude passing through Greenwich.
• GMT – Greenwich Mean Time, the international standard time.
• Time zone – region that uses the same standard time.

Key facts

• 360° in 24 hours → 15° per hour → 1° per 4 minutes
• Time difference = difference in longitude × 4 minutes
• IST longitude: 82°30' E (Mirzapur)
• IST = GMT + 5 hours 30 minutes (82.5 × 4 = 330 minutes)

5 important questions

Q1. Why is local time different at different places?

Because the Earth rotates from west to east, different longitudes face the sun at different times, so noon comes at different times on different longitudes.

Q2. Find the time difference between two places on 75° E and 90° E.

Difference = 15° × 4 minutes = 60 minutes = 1 hour. The place at 90° E is 1 hour ahead.

Q3. When it is 12 noon at Greenwich (0°), what is the local time at a place on 60° W?

60 × 4 = 240 minutes = 4 hours. West is behind, so the time is 8 am.

Q4. Why is standard time necessary?

Using many local times in one country would confuse railways, offices and communication. One standard time keeps the whole country together.

Q5. On which longitude is IST based and how much is it ahead of GMT?

82°30' E passing through Mirzapur; IST is 5 hours 30 minutes ahead of GMT.

Exam tip

Remember: East – add time (ahead), West – subtract time (behind).

Quick summary

The interior of the Earth cannot be seen directly, so scientists study it through volcanic materials, seismic waves, temperature, pressure, density and gravity. This chapter explains how the Earth cooled and formed layers, and describes the crust, mantle and core with their thickness, density, composition and the discontinuities between them.

Key points

• The Earth formed about 4.6 billion years ago as a hot gaseous ball. It cooled from the outside towards the centre, like cream forming on boiled milk – the outer part became the solid crust.
• Evidence about the interior: hot magma and lava from volcanoes, rising temperature in deep mines, and the direction and speed of seismic (earthquake) waves.
• Temperature and density increase with depth.
• The Earth's interior has three main layers: crust, mantle and core.
• Crust (भूकवच): the thinnest, solid outer layer, average 30–35 km thick – about 16–45 km under continents, about 40 km under mountains and less than 10 km under oceans.
• Continental crust: mainly silicon and aluminium (earlier called SIAL), lighter, granite rocks. Oceanic crust: silicon and magnesium (earlier SIMA), 7–10 km thick, density 2.9–3.3 g/cm³, basalt and gabbro rocks.
• Conrad discontinuity lies between the continental and oceanic crust; Mohorovicic (Moho) discontinuity between the crust and mantle.
• Mantle: extends to a depth of about 2870 km; average density 4.5 g/cm³. The upper mantle (asthenosphere) is semi-molten; magma comes from here. The crust and upper solid part of the mantle together form the lithosphere.
• Gutenberg discontinuity separates the mantle and the core.
• Core: made mainly of nickel and iron (earlier NIFE). The outer core is liquid; its movement creates the Earth's magnetic field (magnetosphere). The inner core extends from about 5150 km to the centre at 6371 km; it is very dense (about 13.3 g/cm³).
• The Earth's radius is about 6371 km.

Important terms

• Crust – outermost solid layer of the Earth.
• Mantle – layer below the crust, up to about 2870 km.
• Core – innermost layer made of nickel and iron.
• Discontinuity – boundary zone between two layers.
• Lithosphere – crust plus solid upper mantle.
• Asthenosphere – semi-molten upper part of the mantle.

Key facts

5 important questions

Q1. How do scientists study the interior of the Earth?

By studying materials from volcanic eruptions, the increase of temperature in mines, deep boreholes, and especially the direction and speed of seismic waves, along with density, pressure and gravity.

Q2. Distinguish between continental and oceanic crust.

Continental crust is thicker, lighter and rich in silicon and aluminium (granite). Oceanic crust is thinner (7–10 km), denser and rich in silicon and magnesium (basalt, gabbro).

Q3. Name the discontinuities in the Earth's interior.

Conrad (within the crust), Mohorovicic (crust–mantle) and Gutenberg (mantle–core).

Q4. Why is the core called NIFE?

Because it is mainly made of nickel (Ni) and iron (Fe).

Q5. How is the Earth's magnetic field formed?

Movement of the liquid iron-rich outer core generates a magnetic field around the Earth called the magnetosphere.

Exam tip

Draw the cross-section of the Earth showing all layers, depths and discontinuities – it suits both diagram and short-answer questions.

Quick summary

Moisture (water vapour) in the air is invisible but very important for weather and rainfall. This chapter explains evaporation, humidity and saturation, absolute and relative humidity, condensation, dew point, forms of condensation, and the classification of clouds by altitude, including the rain-bearing nimbostratus and cumulonimbus clouds.

Key points

• Evaporation is the change of water into water vapour due to the sun's heat. It is faster when air is dry, hot and windy, and slower when air is moist, cool and still.
• The proportion of water vapour in the air is humidity (आर्द्रता). Rajasthan has hot, dry air; Kashmir cold, dry air; Mumbai hot, humid air.
• Warm air can hold more vapour than cold air. When air holds as much vapour as it can, it is saturated.
• Absolute humidity is the amount of water vapour in 1 cubic metre of air (g/m³). It is higher near coasts and at the equator.
• Relative humidity is the vapour present expressed as a percentage of the vapour-holding capacity at that temperature. It is higher in mornings and nights and lower in afternoons; high near coasts, low in deserts.
• The temperature at which air becomes saturated is the dew point.
• Condensation: water vapour changing into water; sublimation (here): vapour changing directly into solid ice.
• Condensation needs low temperature, high relative humidity and tiny particles (dust, salt) as nuclei.
• Dew, frost and fog are forms of condensation near the ground; clouds form at higher altitudes.
• A cloud is a collection of tiny water droplets and ice particles floating in the air due to vertical air currents.
• High clouds (7000–14000 m): cirrus, cirrostratus, cirrocumulus – made of ice crystals. Medium clouds (2000–7000 m): altostratus, altocumulus. Low clouds (below 2000 m): stratocumulus, stratus, nimbostratus; cumulus and cumulonimbus may extend to great heights.
• Nimbostratus clouds bring continuous rain or snow. Cumulonimbus clouds are huge, anvil-topped, and cause heavy rain with thunder and lightning (positive charge at top, negative at bottom).

Important terms

• Humidity – amount of water vapour in the air.
• Saturated air – air holding the maximum vapour possible at that temperature.
• Dew point – temperature at which air becomes saturated and condensation begins.
• Condensation – change of water vapour into liquid water.
• Cloud – mass of tiny water droplets and ice crystals floating in the air.

Key facts

• Relative humidity (%) = (Absolute humidity ÷ Vapour-holding capacity) × 100
• High clouds: 7000–14000 m; medium: 2000–7000 m; low: below 2000 m

5 important questions

Q1. Absolute humidity is 20 g/m³ and vapour-holding capacity is 30 g/m³. Find relative humidity.

RH = (20 ÷ 30) × 100 = 66.7%.

Q2. If absolute humidity is 15 g/m³ and holding capacity is 15 g/m³, what is the relative humidity? What is this condition called?

RH = (15 ÷ 15) × 100 = 100%. The air is saturated.

Q3. Why do clothes dry quickly in summer and slowly in the rainy season?

In summer the air is hot and dry, so evaporation is fast. In the rainy season the air is already moist (high relative humidity), so evaporation is slow.

Q4. What conditions are needed for condensation?

Temperature at or below dew point, high relative humidity, and fine particles like dust or salt in the air around which vapour can condense.

Q5. Which clouds bring thunder and lightning? Why?

Cumulonimbus clouds. Their top is positively charged and bottom negatively charged; the difference in charges causes lightning, and the heated air expanding causes thunder.

Exam tip

Remember relative humidity is always a percentage, while absolute humidity is in g/m³.

Quick summary

About 71% of the Earth's surface is covered by water, but beneath the oceans the land is uneven, just like on continents. This chapter describes the relief of the ocean floor – continental shelf, continental slope, abyssal plains, submerged mountains and plateaus, marine deeps and trenches, islands – and the deposits found on the ocean bed.

Key points

• The land submerged under ocean water is the ocean floor (सागरतळ). Its relief depends on depth and shape. Average depth of oceans is about 3700 m.
• Continental shelf: the gently sloping land near the coast under shallow sea water (up to about 200 m). Narrow along some coasts, hundreds of kilometres wide along others.
• The continental shelf is very useful: sunlight reaches it, so plankton and fish are abundant (good fishing grounds), and oil and minerals are obtained, e.g. Mumbai High in the Arabian Sea.
• Continental slope: the steep slope beyond the shelf, from about 200 m to 3600 m deep. Its lower edge is considered the boundary of the continent.
• Abyssal plains: wide, flat, deep plains beyond the continental slope, covered with sediments.
• Submerged mountains and plateaus: mid-oceanic ridges are long underwater mountain ranges; peaks that rise above water form islands such as Iceland (Atlantic) and the Andaman and Nicobar Islands (Bay of Bengal). Example of a submarine plateau: Chagos Plateau in the Indian Ocean.
• Marine deeps are deep depressions; long, narrow and very deep ones are trenches. The Mariana Trench in the Pacific is the deepest, about 11,034 m deep (Mount Everest is 8848 m high).
• Areas near trenches and ridges have active volcanoes and earthquakes; undersea eruptions and quakes can cause tsunamis.
• Marine deposits: pebbles, clay and soil brought by rivers; remains of marine plants and animals; volcanic ash. Sedimentary rocks form from them.
• Human (anthropogenic) waste like plastic is also being deposited on the ocean floor.

Important terms

• Continental shelf – shallow, gently sloping submerged edge of a continent.
• Continental slope – steep slope between the shelf and the deep ocean floor.
• Abyssal plain – flat, deep part of the ocean floor.
• Mid-oceanic ridge – underwater mountain range in the middle of an ocean.
• Trench – long, narrow, very deep depression on the ocean floor.

Key facts

• Water covers about 71% of the Earth's surface
• Average ocean depth ≈ 3700 m
• Continental slope: about 200 m to 3600 m deep
• Mariana Trench: about 11,034 m deep (deepest); Mount Everest: 8848 m high

5 important questions

Q1. Why is the continental shelf important to humans?

It is shallow, so sunlight reaches the bottom and plankton grow, making it a rich fishing area. Oil, natural gas and minerals are also obtained there, e.g. Mumbai High.

Q2. What is a continental slope?

The steep slope beyond the continental shelf, from about 200 m to 3600 m deep; its lower edge is taken as the boundary of the continent.

Q3. What are marine trenches? Give an example.

Long, narrow and very deep depressions on the ocean floor. The Mariana Trench in the Pacific Ocean is the deepest, about 11,034 m.

Q4. How are islands formed from submerged mountains?

When peaks of underwater mountain ranges rise above sea level, they form islands, e.g. Andaman and Nicobar Islands.

Q5. What deposits are found on the ocean floor?

Pebbles, clay and soil from rivers, remains of marine organisms, volcanic ash and also human waste like plastic.

Exam tip

Draw the ocean-floor profile diagram from coast to trench and label each landform – it covers the whole chapter.

Quick summary

Ocean water does not stay still; it flows in definite directions as ocean currents. This chapter explains why currents form (differences in temperature, salinity, density and the effect of winds and the Earth's rotation), warm and cold currents, their direction in the two hemispheres, deep ocean currents, and their effects on climate, fishing, fog, icebergs and transport.

Key points

• When water is heated, its density decreases and it becomes lighter; cooler, denser water moves in to replace it. This sets water in motion – the cause of currents.
• In 1992 about 28,000 rubber toys fell into the Pacific near Hawaii and drifted to distant coasts – showing how ocean currents carry objects.
• Factors forming currents: differences in temperature, salinity and density; prevailing winds; the Earth's rotation; and the shape of coastlines.
• Ocean currents (सागरी प्रवाह) are surface (horizontal) flows of warm or cold water. Warm currents flow from the equator towards the poles; cold currents flow from the poles towards the equator.
• In the Northern Hemisphere, currents generally move clockwise; in the Southern Hemisphere, anti-clockwise. These large circular systems are called gyres.
• Warm currents make the climate of cold coastal regions warmer, e.g. western Europe, southern Alaska and Japan; their ports do not freeze in winter.
• Cold currents make coastal regions cooler and drier; deserts are found where cold currents flow, e.g. Peru–Chile (Atacama) and south-west Africa (Namib).
• Where warm and cold currents meet, plankton grow well, making rich fishing grounds; dense fog also forms, e.g. the warm Gulf Stream and cold Labrador Current meet near Newfoundland.
• Cold currents carry icebergs from polar areas towards lower latitudes, which can be dangerous for ships.
• Deep ocean currents (below about 500 m) form due to differences in density and salinity: cold, dense water sinks and warm water moves to replace it, circulating nutrient-rich water to the surface.
• Ships save time and fuel by sailing along currents.

Important terms

• Ocean current – continuous movement of ocean water in a definite direction.
• Warm current – current flowing from warmer to colder regions.
• Cold current – current flowing from colder to warmer regions.
• Gyre – large circular system of ocean currents.
• Salinity – amount of dissolved salts in sea water.

Key facts

• Warm currents: Gulf Stream, Kuroshio, Brazil Current
• Cold currents: Labrador, Humboldt (Peru), Benguela, Canary, California
• Northern Hemisphere – clockwise; Southern Hemisphere – anti-clockwise

5 important questions

Q1. What are the effects of warm ocean currents on climate?

They raise the temperature of cold coastal regions, reduce the severity of winter and keep ports ice-free, e.g. western Europe and Japan.

Q2. How does the Humboldt (Peru) current affect the South American coast?

It is a cold current, so it cools the coast and reduces rainfall, creating dry desert conditions in Peru and Chile; it also makes the area a rich fishing ground.

Q3. What happens where warm and cold currents meet?

Dense fog forms, and plankton grow well, creating rich fishing grounds, e.g. near Newfoundland.

Q4. What are the reasons for deep ocean currents?

Differences in temperature, salinity and density – cold, salty, dense water sinks and moves along the bottom while warmer water rises.

Q5. Why do cold currents carry icebergs?

Cold currents flow from polar regions towards the equator, so they carry floating icebergs to lower latitudes.

Exam tip

On a world map, mark warm currents with red arrows and cold currents with blue arrows – map questions are common.

Quick summary

Land use is the way or purpose for which land in a region is used. This chapter explains how land use develops from the interaction between geographical factors and human needs, compares rural and urban land use and their categories, describes planned cities, and explains land ownership records like the 7/12 extract and the property card.

Key points

• Land use (भूमी उपयोजन) changes with time as human needs grow. Mineral-rich land is used for mining; fertile plains for agriculture.
• Rural land use: agriculture is the main occupation, so settlements are near fields and forests (miners near mines, fishermen near the sea). Population is sparse and residential area is small.
• Rural categories: arable land (land under cultivation, mostly privately owned); fallow land (left uncultivated for one or two seasons to restore fertility); forest land (gives firewood, gum, grass); grazing land/pasture (gairan, mostly owned by the village panchayat or government); settlements.
• Urban land use: cities grew fast in the 20th century; population is dense and land is used for many purposes.
• Urban categories: commercial (shops, banks, offices – Central Business District or CBD); residential; transport (roads, railways, bus stops, airports, ports); public utilities (hospitals, post offices, police stations, schools); recreational (gardens, grounds, swimming pools, theatres); and mixed land use.
• Between a city and villages lies a transitional area (suburbs) where rural and urban uses mix.
• Planned cities are designed with land for each use in advance: Washington DC (USA), Brasilia (Brazil), Chandigarh and Bhubaneswar (India).
• Factors affecting land use: location and site, climate, soil, natural resources, housing and development needs.
• Land ownership can be private or public. The revenue department keeps records.
• The 7/12 extract (satbara utara) combines Village Form No. 7 and No. 12; it shows the owner, area, crops, loans and transfers of agricultural land. It is kept by the Talathi of the village.
• Occupant Class 1: ancestral land with full ownership rights. Occupant Class 2: land given by the government to marginal or landless farmers; it can be sold or transferred only with government sanction.
• Ownership of non-agricultural (urban) land is recorded on the property card.

Important terms

• Land use – the purpose for which land is used.
• Fallow land – farm land kept uncultivated for a season or two to regain fertility.
• CBD – Central Business District, the main commercial area of a city.
• Transitional area – zone between urban and rural areas.
• 7/12 extract – record of agricultural land ownership in Maharashtra.

Key facts

• Map colours: red – residential, blue – commercial, yellow – agricultural, green – forest
• 7/12 = Village Form 7 + Village Form 12 (kept by the Talathi)
• Planned cities: Chandigarh, Bhubaneswar, Washington DC, Brasilia

5 important questions

Q1. Distinguish between rural and urban land use.

Rural land is used mainly for agriculture, forests and grazing; population is sparse. Urban land is used for residence, commerce, industry, transport and recreation; population is dense.

Q2. What is fallow land?

Agricultural land left uncultivated for one or two seasons to improve soil fertility.

Q3. What information does a 7/12 extract give?

Owner of the land, its area, type of ownership, crops grown, loans and debts on it, and transfers of ownership.

Q4. What is meant by a transitional area?

The area between the edge of a city and the surrounding villages, where urban and rural land uses are mixed (suburbs).

Q5. What is a planned city? Give examples.

A city where land for each use is decided and designed before construction, e.g. Chandigarh, Bhubaneswar, Brasilia.

Exam tip

Learn the difference between Occupant Class 1 and Class 2 – it is a favourite "give reason / distinguish" question.

Quick summary

Population is an important factor in the development of a region. This chapter explains population growth (births, deaths, migration), factors affecting the distribution of population, population density, and the structure of population – sex ratio, age structure, literacy, rural–urban and working population – and how population quality affects development.

Key points

• Population of a region changes constantly due to births, deaths and migration.
• Birth rate: number of live births per 1000 people in a year. Death rate: number of deaths per 1000 people in a year.
• Life expectancy: the average number of years a person born in an area is expected to live.
• Migration (स्थलांतर): movement of people into an area (in-migration) or out of an area (out-migration) for residence.
• Factors affecting population distribution: physical (location, relief, climate, soil, water), economic (agriculture, industry, urbanisation, transport), political (wars, instability, government policy) and social (race, religion, language).
• Fertile plains with good climate and jobs have dense population; deserts, mountains and dense forests have sparse population.
• Population density is the number of people per square kilometre.
• Population structure means dividing population by sex, age, literacy, rural/urban residence and work.
• Sex ratio is the number of females per 1000 males. A low sex ratio shows fewer women and is a social concern.
• Age structure: children (0–14), productive or working age (15–59) and old (60 and above). The productive group directly takes part in economic activities; children and the old are dependent.
• A literate, healthy and skilled population helps development; quality of population matters as much as quantity.
• Population data in India is collected by the Census every 10 years (last in 2011).

Important terms

• Birth rate – live births per 1000 people per year.
• Death rate – deaths per 1000 people per year.
• Migration – movement of people from one place to another to live.
• Population density – number of people per sq km.
• Sex ratio – number of females per 1000 males.
• Productive population – people aged 15 to 59 years.

Key facts

• Density = Total population ÷ Area (sq km)
• Sex ratio = (Number of females ÷ Number of males) × 1000
• Population change = births − deaths + in-migration − out-migration
• Uttar Pradesh 2011: 19,98,12,341 people ÷ 2,40,926 sq km ≈ 829 per sq km

5 important questions

Q1. Calculate the population density of Goa (2011): population 14,58,545, area 3,702 sq km.

Density = 14,58,545 ÷ 3,702 ≈ 394 persons per sq km.

Q2. A town has 5000 males and 4600 females. Find the sex ratio.

Sex ratio = (4600 ÷ 5000) × 1000 = 920 females per 1000 males.

Q3. A city had 1,00,000 people. In a year there were 2,000 births, 1,500 deaths, 23,000 in-migrants and 2,000 out-migrants. Find the new population.

1,00,000 + 2,000 − 1,500 + 23,000 − 2,000 = 1,21,500.

Q4. What are the physical factors affecting population distribution?

Location, relief (plains or mountains), climate, soil fertility and availability of water.

Q5. Why is the productive population important?

People aged 15–59 work and take part in economic activities; they support the dependent children and old people and drive the region's development.

Exam tip

Always write the units: density in persons per sq km, sex ratio in females per 1000 males, birth/death rate per 1000.

Quick summary

Industries convert raw materials into more useful finished products and provide secondary occupations. This chapter explains the factors affecting the location of industries, classification of industries by size and raw material, agro-based industries, industrial estates (MIDC), the information technology industry, industrial pollution and Corporate Social Responsibility (CSR).

Key points

• The process of converting raw material into finished products in factories is manufacturing. The finished product is more durable, useful and has added value.
• Industries (उद्योग) speed up economic development, create jobs and raise per capita income.
• Factors affecting location: raw material, water, energy (power), labour, capital, transport, market, land and government policy. Because these are unevenly distributed, industrial development is uneven.
• Iron and steel industry needs heavy, bulky raw materials (iron ore, coal), so it is set up near them – e.g. Jamshedpur, where raw material and energy are available.
• Sugar factories are set up near sugarcane fields because cane must be crushed quickly.
• By size: small industries (earthen pots, candles, agarbatti), medium (fruit processing, jaggery) and heavy industries (cement, sugar, iron and steel).
• By raw material: agro-based (cotton textiles, sugar, jaggery, oil mills, dairy, fruit and food processing), forest-based (paper, furniture), mineral-based (iron and steel, cement) and others.
• India is an agrarian country, so agro-based industries are very important; they increase farmers' income.
• Industrial estates such as MIDC (Maharashtra Industrial Development Corporation) provide roads, water, electricity and plots; auxiliary industries develop around big units.
• Information Technology industry: collecting, processing, presenting and supplying information; its main requirement is skilled manpower (e.g. IT parks in Pune, Mumbai, Bengaluru, Hyderabad).
• Industries cause air, water, soil and noise pollution (industrial pollution). Proper treatment and disposal of waste is required; laws exist to control pollution.
• Corporate Social Responsibility (CSR): companies with profits above ₹ 5 crore are expected to spend at least 2% of their profits on society and environment; tax rebate is given on it.

Important terms

• Raw material – natural or semi-finished material used to make products.
• Agro-based industry – industry using agricultural products as raw material.
• Industrial estate – area developed with facilities for setting up industries.
• Industrial pollution – pollution caused by industries.
• CSR – a company's duty to work for society and the environment.

Key facts

5 important questions

Q1. What factors affect the location of an industry?

Availability of raw material, water, power, labour, capital, transport, market and land, along with government policies.

Q2. Why is the iron and steel industry located near raw material?

Its raw materials (iron ore, coal, limestone) are heavy and bulky, so transporting them far is costly; hence it is set up near their source, like Jamshedpur.

Q3. What is the importance of agro-based industries in India?

India is an agrarian country; these industries use farm products, add value, give employment in rural areas and increase farmers' income.

Q4. What is Corporate Social Responsibility?

When companies work for the welfare of society and environmental protection. Companies with profit over ₹ 5 crore are expected to spend at least 2% of profit on such work.

Q5. What is the most important factor for the IT industry?

Availability of skilled manpower.

Exam tip

For location questions, name the most important factor first (raw material, power, market or skilled labour) and then give an example.

Quick summary

A large area of the Earth can be shown on a small sheet of paper only by reducing all distances in a fixed ratio called the scale. This chapter explains the meaning of map scale, the three ways of showing scale (verbal, numerical and linear/graphical), converting one to another, measuring distances on a map, and the difference between large-scale and small-scale maps.

Key points

• A painter estimates the proportions of a scene before drawing; similarly a map is drawn after survey using a fixed scale.
• Map scale (प्रमाण) is the ratio between the distance between two points on a map and the actual distance between them on the ground.
• Verbal scale (statement scale): expressed in words, e.g. 1 cm = 10 km.
• Numerical scale (representative fraction, R.F.): expressed as a ratio without units, e.g. 1:60,00,000 – 1 unit on the map = 60,00,000 same units on the ground. It can be used with any unit.
• Linear or graphical scale: a line divided into equal parts showing ground distances.
• Converting verbal to numerical: 1 cm = 60 km → 1 km = 1,00,000 cm, so 60 km = 60,00,000 cm → 1:60,00,000.
• To measure distance: measure the map distance with a ruler (a thread or divider for curved roads/rivers) and multiply by the scale.
• When a map is enlarged or reduced (photocopy, screen), the verbal and numerical scales become wrong, but the graphical scale changes along with the map – so the graphical scale remains correct. This is its main importance.
• Large-scale maps show a small area in great detail, e.g. village or city maps, building plans (scale like 1:10,000 or larger).
• Small-scale maps show a large area with less detail, e.g. maps of countries, continents and the world, atlas maps.

Important terms

• Scale – ratio of map distance to ground distance.
• Verbal scale – scale written as a statement in words.
• Representative fraction (R.F.) – scale written as a ratio like 1:50,000.
• Graphical (linear) scale – scale shown as a divided line.
• Large-scale map – map of a small area with more detail.

Key facts

• 1 km = 1000 m = 1,00,000 cm
• Ground distance = map distance × scale value
• 1 cm = 1 km → 1:1,00,000; 1 cm = 10 km → 1:10,00,000; 1 cm = 60 km → 1:60,00,000

5 important questions

Q1. Convert the verbal scale 1 cm = 10 km into a numerical scale.

10 km = 10 × 1,00,000 cm = 10,00,000 cm. So the numerical scale is 1:10,00,000.

Q2. On a map with scale 1 cm = 10 km, two villages are 4.5 cm apart. Find the actual distance.

4.5 × 10 = 45 km.

Q3. Convert the numerical scale 1:50,000 into a verbal scale.

1 cm on map = 50,000 cm on ground = 0.5 km. Verbal scale: 1 cm = 0.5 km.

Q4. Why is the graphical scale useful?

When a map is enlarged or reduced, the graphical scale also changes in the same proportion, so distances measured with it remain correct; verbal and numerical scales would become wrong.

Q5. Distinguish between large-scale and small-scale maps.

Large-scale maps show a small area in detail (village, city plans). Small-scale maps show a large area with less detail (country, world maps).

Exam tip

Always convert km to cm (× 1,00,000) before writing a numerical scale.

Quick summary

A field trip is an important method of learning geography through first-hand experience. This chapter explains how to plan and conduct a field trip, what to carry, how to prepare a questionnaire and write a report, using the example of a visit to the election office at the taluka or district level.

Key points

• Field trips (क्षेत्रभेट) give first-hand experience of geographical factors and processes and help us understand the relationship between man and environment.
• A field trip should be planned according to the topic, place and duration of the visit.
• One aim of a field trip is to visit an office and understand the work done there.
• Information is collected using a questionnaire – a list of planned questions. After the visit the information is compiled and a report is written.
• Kit for the trip: copy of the questionnaire, notebook, camera, pen and pencil.
• Prior permission must be taken from the office before fixing the date and time. Students must behave properly and not damage anything.
• Sample visit – election office: who heads the office; duties of the office; how voter lists are prepared and updated; how staff are trained; how many people work at a polling booth; voting timings; how postal votes of election staff are taken.
• Questions also cover Electronic Voting Machines (EVMs) – how they are obtained, their advantages, what to do if one fails, and how voting was done earlier with ballot papers.
• Other topics: Model Code of Conduct and how long it applies, when by-elections are held, what happens if candidates get equal votes, who declares results and how records are kept.
• Similar questionnaires can be prepared for visits to a Talathi office, a small-scale industry, a dam, a market or a weather station.
• Report writing: introduction (place, date, purpose), information collected, observations, conclusion, photographs/sketches and acknowledgement.

Important terms

• Field trip – educational visit to a place for direct observation and information.
• Questionnaire – set of questions prepared in advance to collect information.
• Report – organised written account of the information collected.
• EVM – Electronic Voting Machine used in elections.
• Code of Conduct – rules that parties and candidates must follow during elections.

Key facts

Steps of a field trip:

1. Choose topic and place; get permission
2. Prepare the questionnaire and kit
3. Visit, observe, ask questions, take notes and photos
4. Compile information and write the report

5 important questions

Q1. Why are field trips important in geography?

They give first-hand experience, help understand geographical concepts and processes, and show the relationship between man and environment.

Q2. What preparations are needed for a field trip?

Selecting the place and topic, taking prior permission, preparing a questionnaire, and carrying a notebook, pen, pencil and camera.

Q3. What is a questionnaire? Why is it needed?

A list of questions prepared before the visit. It helps collect complete and organised information without forgetting anything.

Q4. Write any four questions you would ask at an election office.

What are the duties of this office? How are voter lists updated? What are the voting timings? What are the advantages of EVMs?

Q5. What points should a field trip report include?

Name of place, date and purpose, information collected, observations, conclusions, photographs or sketches, and thanks to the officials.

Exam tip

Practise preparing a 10-question questionnaire for any one office – it is a common activity-based question.