A map and its components
When you get off a train in a strange city and must find a bank or a garden, you look at a map or ask a local person.
A map is a drawing of an area as if seen from above. An atlas is a book of maps. A map has three main components: distance (scale), direction and symbols.
In the figure : The three kinds of maps and their three components.
A map and its components
In the app you can move this figure with your finger.
Open in the appRule 1: The scale lets a big place fit on small paper — Each centimetre on the map stands for a fixed distance on the ground; this is the scale.
- Easy : If 1 cm = 5 km, then 6 cm on the map means 30 km.
- Medium : On a scale of 1 cm = 10 m, a 40 m × 30 m ground is drawn as 4 cm × 3 cm.
- Exam-type : Why is a scale needed? Answer: it lets us find the real ground distance from the distance measured on the map.
Rule 2: Directions and symbols make a map easy to read — There are four cardinal directions: north, east, south, west. Between them lie northeast, southeast, southwest and northwest. Symbols save space by standing for buildings, roads, rivers and so on.
- Easy : The arrow marked N on a map points north.
- Medium : If your home is south of the school, the school is north of your home.
- Exam-type : Who fixes the symbols for maps of India? Answer: the Survey of India, a government body.
A map is like a treasure guide; it shows where things are and how to reach them.
Assuming the top of every map is north. Check the N arrow first.
Read a map in this order: title, scale, direction, symbols. Memory clue : T-S-D-S (Title, Scale, Direction, Symbols).
Spot the difference
| Term | Meaning | Example |
|---|---|---|
| Physical map | Shows natural features | Mountains, rivers |
| Political map | Shows countries, states, cities | India with its states |
| Thematic map | Information on one topic | A rainfall map |
| Scale | Link between map and ground distance | 1 cm = 500 m |
Practice questions
- 1What is a map?
- 2Name the three components of a map.
- 3What is an atlas?
- 4Name the four cardinal directions.
- 5If the scale is 1 cm = 2 km, how many km do 9 cm on the map stand for?
- 6State the difference between a political and a physical map.
- 7Why are symbols used instead of drawing every building on a large map?
- 8A ground is 60 m × 40 m. On a scale of 1 cm = 10 m, what will its length and width be on the map?
Show answers (try them yourself first)
- 1A drawing of an area as seen from above.
- 2Distance (scale), direction and symbols.
- 3A book or collection of maps.
- 4North, east, south and west.
- 59 × 2 = 18 km.
- 6A political map shows countries, states and cities; a physical map shows natural features such as mountains, rivers and oceans.
- 7Space is limited; symbols let us show many details in a small space.
- 8Length 60 ÷ 10 = 6 cm, width 40 ÷ 10 = 4 cm.
Mapping the Earth: the globe and latitude
In a market you say, "the fifth shop in the seventh row". Two numbers fix the spot exactly; chess also uses a letter and a number such as d2 or d4.
A globe is a round model of the Earth. The two numbers that fix a place are its coordinates. Latitude is the distance north or south of the Equator, measured in degrees.
In the figure : How latitude works: 0° to 90° north and south.
Rule 1: Latitude is counted from the Equator — The Equator is the largest circle. Circles parallel to it (parallels of latitude) get smaller towards the poles.
- Easy : The Equator is at 0° and the poles at 90° latitude.
- Medium : Delhi is 29°N and Bengaluru 13°N, so Delhi is farther from the Equator.
- Exam-type : Which parallel is the longest? Answer: the Equator.
Rule 2: Latitude and climate are linked — Near the Equator it is hot, further out it is moderate, and near the poles it is very cold.
- Easy : Regions near the Equator are hot.
- Medium : Regions at middle latitudes have a moderate climate.
- Exam-type : Why is it colder near the poles? Answer: the Sun's rays fall slantwise there (you will learn why in Science).
The Earth is not a perfect sphere; it is slightly flattened at the poles, but we treat it as round.
Thinking parallels run north-south. They are east-west circles.
Latitude = horizontal lines, counted from the Equator. Memory clue : Latitude lines are flat, like ladder rungs.
Spot the difference
| Term | Meaning | Example |
|---|---|---|
| Coordinates | Two values that fix a place | d2 → d4; 29°N, 77°E |
| Latitude | Distance north/south of the Equator (degrees) | Delhi 29°N |
| Parallel of latitude | Imaginary circle parallel to the Equator | The Equator is one itself |
| Globe | Round model of the Earth | The globe in class |
Practice questions
- 1What is a globe?
- 2From where is latitude measured?
- 3What is the latitude of the North Pole?
- 4What is a parallel of latitude?
- 5Mumbai is at 19°N and Chennai at 13°N. Which is nearer the Equator?
- 6Using the word "latitude", explain why places near the Equator are hot.
- 7Why do parallels get smaller towards the poles?
- 8What is common between "d2 to d4" in chess and latitude-longitude?
Show answers (try them yourself first)
- 1A round model of the Earth.
- 2From the Equator.
- 390°N.
- 4An imaginary east-west circle parallel to the Equator.
- 5Chennai, because its latitude is smaller.
- 6At low latitudes (near the Equator) the Sun's rays fall more directly, so it is hot.
- 7The round Earth is widest at the Equator and narrows towards the poles.
- 8In both, two coordinates fix a position exactly.
Longitude and the Prime Meridian
At one place it is breakfast time, at another lunch and at a third people are asleep — the Earth turns, so time changes with place.
A meridian is a half-circle from pole to pole. The Prime Meridian (0°) passes through Greenwich. Longitude is the east-west distance from the Prime Meridian.
In the figure : How longitude works and the grid it forms with latitude.
Rule 1: Longitude is counted from the Prime Meridian — In 1884 some nations agreed that the meridian through Greenwich (London) would be the world's Prime Meridian. Degrees run from 0° to 180° east and west of it.
- Easy : Greenwich lies at 0° longitude.
- Medium : Delhi is 77°E and Tokyo 140°E; both are east, but Tokyo is farther east.
- Exam-type : Are 180°E and 180°W different? Answer: no, it is the same meridian, simply called 180°.
Rule 2: Latitude + longitude give the full address — Together they fix any place exactly. The network of lines is called a grid.
- Easy : Delhi lies at 29°N, 77°E.
- Medium : India extends roughly from 8°N to 37°N and from 68°E to 97°E.
- Exam-type : Why is latitude alone not enough? Answer: many places lie along the same east-west circle; longitude is needed too.
India too had an ancient prime meridian — the "madhya rekha" through Ujjayini; astronomers such as Varahamihira used it some 1,500 years ago.
Thinking meridians are horizontal. They run north-south.
Longitude = vertical lines, counted from the Prime Meridian. Memory clue : Longitude lines run pole to pole, like orange segments.
Spot the difference
| Term | Meaning | Example |
|---|---|---|
| Meridian | Half-circle from pole to pole | Greenwich meridian |
| Prime Meridian | The 0° meridian | Greenwich, London |
| Longitude | East-west distance from it (degrees) | Tokyo 140°E |
| Grid | Network of latitude and longitude lines | The blue lines on a globe |
Practice questions
- 1What is a meridian?
- 2Through which place does the Prime Meridian pass?
- 3Up to how many degrees is longitude measured?
- 4Give the coordinates of Delhi.
- 5How was the Prime Meridian fixed in 1884?
- 6What was the Ujjayini "madhya rekha"?
- 7Why do the old cities not lie exactly on the Ujjayini line?
- 8If two places have the same latitude but different longitudes, how are they placed?
Show answers (try them yourself first)
- 1A half-circle running from pole to pole.
- 2Greenwich (London).
- 3Up to 180° east and 180° west.
- 4About 29°N and 77°E.
- 5Some nations agreed to treat the meridian through Greenwich as the world's Prime Meridian.
- 6The prime meridian through Ujjayini that ancient Indian astronomers used as reference.
- 7Measuring longitude needs accurate time, and the clocks of those days were less exact than today's.
- 8They lie on the same parallel, but at different points east-west.
Time zones and the International Date Line
On a phone call a friend in Porbandar says "it is still daylight" while a friend in Assam says "it is already dark!" — their times differ.
The Earth turns 360° in 24 hours, which is 15° each hour, so time changes by 1 hour for every 15° of longitude. Local time is the Sun-based time of a place; standard time is the one time a country follows.
In the figure : The rule 15° = 1 hour, and India's standard time.
Time zones and the International Date Line
In the app you can move this figure with your finger.
Open in the appRule 1: Time changes with longitude — If it is 12 noon at Greenwich, it is 1 pm at 15°E and 11 am at 15°W. East is ahead, west is behind.
- Easy : At 45°E the time is 3 hours ahead of Greenwich; if Greenwich shows 12, it is 3 pm there.
- Medium : Bengaluru and Delhi have almost the same longitude (77°E), so their local times do not differ.
- Exam-type : If Porbandar and Tinsukia differ by 30° of longitude, what is the time difference? Answer: 30 ÷ 15 = 2 hours.
Rule 2: Countries use one standard time — Many local times would be inconvenient, so a country follows the time of one meridian. Indian Standard Time (IST) is 5 hours 30 minutes ahead of Greenwich time. Very large countries (USA 6, Russia 11) use several time zones.
- Easy : When it is 12 noon in London it is 5:30 pm in India.
- Medium : If GMT shows 6 am, IST shows 11:30 am.
- Exam-type : What changes when you cross the International Date Line eastward? Answer: you subtract a day (Monday becomes Sunday).
The Date Line lies near 180° but bends in places so that a country is not split into two different days.
Thinking time zone lines are always straight meridians. They bend to follow country borders.
Difference in degrees ÷ 15 = hours; add going east, subtract going west. Memory clue : East = ahead, west = behind (the Sun rises in the east first).
Spot the difference
| Term | Meaning | Example |
|---|---|---|
| Local time | Sun-based time at that place | Porbandar and Tinsukia differ |
| Standard time | The single time a country follows | IST = GMT + 5:30 |
| Time zone | A belt with one standard time | Russia has 11 |
| International Date Line | The line near 180° where the date changes | Crossing eastward: -1 day |
Practice questions
- 1How many degrees does the Earth turn in one hour?
- 2What is IST?
- 3At about which longitude is the International Date Line?
- 4If it is 12 noon at Greenwich, what is the time at 30°E?
- 5If it is 12 noon at Greenwich, what is the time at 45°W?
- 6Explain the difference between local time and standard time.
- 7Why do the USA and Russia have many time zones?
- 8Why is the Date Line drawn bent near 180°?
Show answers (try them yourself first)
- 115°.
- 2Indian Standard Time.
- 3180°.
- 430 ÷ 15 = 2 hours ahead, so 2 pm.
- 545 ÷ 15 = 3 hours behind, so 9 am.
- 6Local time differs from place to place with the Sun; standard time is the time of one chosen meridian used for the whole country.
- 7These countries stretch very far east-west, so one time would not suit all places.
- 8So that no country is split into two different days.