Chapter - 1, Locating Places on the Earth
The globe of the Earth stands in space, made upof water, earth, fire and air and is spherical..... It is surrounded by all creatures, terrestrial as well as aquatic. ( Aryabhata - about--500 CE)
A Map and Its Components
What is a Map?
- A drawing of the Earth's surface (or a part of it) on a flat surface.
- Maps give more detailed information than a globe.
- Made using symbols, colors, scales, and directions.
An atlas is a book or collection of maps.
Types of Maps
- Physical Maps:- Maps shows some natural features: mountains, rivers, plains, etc.
- Political Maps:- Maps Show boundaries: countries, states, cities.
- Thematic Maps:- Maps Show specific information: rainfall, population, crops, etc.
Components of a Map
1. Distance (Scale):- The relationship between distance on the map and actual distance on the ground.
Example: 1 cm on map = 10 km on ground.
Types of scales:
- Small Scale: Large areas with less detail (e.g., country map).
- Large Scale: Small areas with more detail (e.g., city map).
2. Direction:- Most maps show north at the top.
Cardinal Directions: North (N), South (S), East (E), West (W).
Intermediate Directions: NE, NW, SE, SW.
3. Symbols:- Used to show features like roads, rivers, railways, bridges, temples, etc.
A legend or key explains what each symbol means.
Symbols make maps easy to read and compact.
Mapping the Earth
- Mapping on the Earth is a little more difficult because our planet is not a flat surface.
- It nearly has the shape of a sphere.
- It is slightly flattened at the poles.
- Representing a sphere accurately on a flat sheet of paper is not possible.
- The Earth is very big and round, so we can’t see or study all of it at once.
- Maps and globes help us understand and locate places on Earth.
Understanding Coordinates:- Coordinates are a set of numbers (latitude and longitude) used to locate a place on Earth accurately.
1. Latitude:- Horizontal imaginary lines.
- Measure north or south of the Equator (0° latitude).
- Goes up to 90° North and 90° South.
- Examples:
- Tropic of Cancer: 23½° N
- Tropic of Capricorn: 23½° S
2. Longitude:- These lines are called meridians of longitude.
- Vertical imaginary lines.
- Measure east or west of the Prime Meridian (0° longitude).
- Goes up to 180° East and 180° West.
- Prime Meridian passes through Greenwich, England.
3. How Coordinates Work
- A place is located using both latitude and longitude.
- Example: Delhi, India is located approximately at 28.6° N latitude and 77.2° E longitude.
- Latitude + Longitude = Coordinate of a place
- The point where latitude and longitude intersect gives the exact location.
- Used in GPS, maps, and atlases.
Understanding Time Zones
Why Do We Have Time Zones?
- The Earth rotates from west to east and completes one full rotation (360°) in 24 hours.
- So, it rotates 15° every hour (360° ÷ 24 = 15°).
- Because of this, different parts of the Earth experience day and night at different times.
- To manage this, the world is divided into 24 time zones, each 15° apart.
Why do most countries adopt standard time?
Most countries adopt standard time to maintain a uniform time across the country, avoid confusion due to local times, and to ensure smooth running of transport, communication, business, and government activities.
What is GMT?:- GMT stands for Greenwich Mean Time.
- the time measured at the Prime Meridian (0° longitude), and it is used as the reference for all time zones in the world.
- It is the base time for all the time zones in the world.
- Countries calculate their own time by adding or subtracting hours from GMT.
- Example: India is GMT + 5½ hours (Indian Standard Time).
What Is the International Date Line (IDL)?
- The International Date Line (IDL) is an imaginary line on the globe that marks where the date changes by one day.
- It is located at approximately 180° longitude.
- When you cross the IDL from west to east, you subtract a day (go back one day).
- When you cross from east to west, you add a day (go forward one day).
NCERT QUESTIONS
O1. Returning to page 10 and to Fig. 5.2 in Chapter 5 of this textbook, taking the scale to be 2.5 cm = 500 km, calculate the real distance from the estuary of the Narmada River to the estuary of the Ganga river. (Hint: round off your measurement on the map to an easy number.)
Answers:- Given:- Scale: 2.5 cm on the map = 500 km in real life
Distance on the map (between the estuaries of the Narmada and Ganga rivers): Let’s assume or round off the map distance to 6 cm (as suggested in the NCERT hint).
The real distance from the estuary of the Narmada River to the estuary of the Ganga River is approximately 1200 km.
Q2. Why is it 5:30 p.m. in India when it is 12:00 noon in London?
Answers: India is 82½° east of the Prime Meridian. Every 15° = 1 hour, so 82½° = 5½ hours. Hence, India is 5 hours 30 minutes ahead of London.
Q3. Why Do We Need Symbols and Colours in a Map?
Answers. We use symbols and colours in a map to show different features clearly, save space, and make the map easy to read. Symbols represent things like roads and rivers, while colours help identify landforms like mountains, water, and plains.
Q4. Find Out What You Have in the Eight Directions from Your Home and School?
Answers. Main directions: North, South, East, West
Sub-directions: North-East (NE), South-East (SE), South-West (SW), North-West (NW).
Example:- From My Homeand school:
Direction (Home/School)What I See
North Park/Library
South Grocery shop/Sschool Gate
East Main road/School Field
West Neighbor’s house/Staff Room
North-East (NE) Temple/Drinking Water
South-East (SE) Bus stop/Science Lab
South-West (SW) Community hall/Rest Room
North-West (NW) School playground/Music Room
Q5. What is difference between local time and standard time? discuss it in groups, with each group writing an answer in 100 to 150 words. compare your answers.
Answers. Difference Between Local Time and Standard Time
Local time is the time calculated for a particular place based on the position of the sun. When the sun is exactly overhead at a place, it is 12 noon there. This means each place along different longitudes can have a slightly different local time.
But using different local times for every city causes confusion. So, countries use a standard time, which is the time fixed for the whole country based on one central longitude. For example, in India, the standard time is based on 82½° E longitude and is called Indian Standard Time (IST).
Standard time helps with organizing transport, communication, and government activities across the country. Local time is mostly used in astronomy or older systems.
Q6. Delhi's and Bengaluru's latitudes are 29 degree N and 13 degree ; their longitudes are almost the same, 77 degree E. How much will be the difference in local time between the two cities?
Answers:- No, there will be no difference in local time.
Q7. Mark the following statements as true or false; explain your answers with a sentence or two.
1. Do parallels of latitude have the same length?
A: False, parallels of latitude do not have the same length. The Equator is the longest, and the length of the parallels decreases as we move towards the poles.
2. Is the length of the meridian of longitude half of that of the equator?
A: False, the meridian of longitude runs from the North Pole to the South Pole, and it forms a semi-circle. It is not half the length of the Equator, as both are different in shape and orientation.
3. The South Pole has a latitude of 90° S.
A: True, the latitude of the South Pole is 90° S, which is the southernmost point on Earth.
4. In Assam, the local time and IST are identical.
A: True, the local time and Indian Standard Time (IST) are identical in Assam, even though Assam lies to the east of the IST meridian. India uses one standard time (IST) across the country, which is based on 82½° E longitude.
While some regions in Assam, particularly tea gardens, have historically used a time zone one hour ahead of IST (Chaibagan or "Tea Garden Time"), this is an informal practice and does not represent the official time zone for the state. The official time zone for Assam, as well as the rest of India, is IST.
5. Lines seperating the time zonnes are identical with meridians of longitudes.
Answer: True, the lines separating time zones are based on meridians of longitude, but they are not always identical to them.
6. The Equator is also a parallel of latitude.
A: True, the Equator is the zero-degree parallel of latitude, dividing the Earth into the Northern and Southern Hemispheres. It is the longest parallel of latitude.
