Std 6 – Geography
Chapter 3: World of Coordinates
Do You Know?
India had its own Prime Meridian before the 0° Greenwich longitude was internationally accepted. This line, called the central meridian, was considered to pass through the city of Ujjayini (Ujjain), which was the centre for astronomical studies in India for many centuries. About 1500 years ago, the famous astronomer Varahmihir lived and studied at Ujjain. Indian astronomers understood the concepts of angular distances and longitudes, and realised the need for a zero line or Prime Meridian. The Ujjaini Prime Meridian became the reference point for all Indian astronomical calculations found in ancient Indian astronomical texts.
Exercise A: Solve the Following Questions as Directed
1) Choose the correct option by matching the right pairs from the ‘A’ and ‘B’ groups.
| ‘A’ | ‘B’ |
|---|---|
| 1. Tropic of Cancer | A. 23° 30′ South |
| 2. Tropic of Capricorn | B. 23° 30′ North |
| 3. The Antarctic Circle | C. 66° 30′ North |
| 4. The Arctic Circle | D. 66° 30′ South |
Ans: The correct option is (b) 1-B, 2-A, 3-D, 4-C. The Tropic of Cancer lies at 23°30′ North, the Tropic of Capricorn lies at 23°30′ South, the Antarctic Circle lies at 66°30′ South, and the Arctic Circle lies at 66°30′ North.
2) Identify which are the true statements about latitudes and longitudes and choose the correct option.
1. The 0° latitude divides the Earth into two equal hemispheres. — True
2. The 0° and the 180° longitudes together divide the earth into the eastern and the western hemispheres. — True
3. The length of all the longitudes is equal. — True
4. All latitudes are of equal length. — False
Ans: The correct option is (B) 1, 2, 3. Statements 1, 2 and 3 are true. Statement 4 is false because all latitudes are not of equal length; the length of latitude circles keeps decreasing as we move away from the Equator towards the poles, and at the poles the latitude reduces to just a point.
3) Examine the following statements, correct the incorrect statements and rewrite.
1. All longitudes converge at the north and the south poles. — Correct as it is. Ans: All longitudes converge (meet) at the North Pole and the South Pole.
2. The consecutive longitudes are parallel to each other. — Incorrect. Ans: The consecutive longitudes are not parallel to each other; they converge towards the North Pole and the South Pole.
3. The 180° longitude is the base longitude. — Incorrect. Ans: The 0° longitude (the Greenwich Prime Meridian) is the base longitude, not the 180° longitude.
4. The base longitude divides the Earth into the northern and the southern hemispheres. — Incorrect. Ans: The base longitude (0°), together with the 180° longitude, divides the Earth into the eastern and the western hemispheres. It is the Equator (0° latitude) that divides the Earth into the northern and the southern hemispheres.
5. The equator is also called the Great Circle. — Correct as it is. Ans: The Equator is also called the Great Circle because it is the largest latitude circle and divides the Earth into two equal halves.
Exercise B: Identify the Features with the Help of a Globe
1. The tropic of Cancer, the tropic of Capricorn, the Equator, the base longitude
Ans: These are the main imaginary reference circles/lines drawn on a globe used to locate places — the Equator and base longitude (Prime Meridian) being the 0° reference lines, and the Tropic of Cancer and Tropic of Capricorn being important latitudes.
2. The 90° East, 90° West, the 5° East, 90° North
Ans: 90°E, 90°W and 5°E are examples of longitudes (meridians), while 90°N is not a longitude — it denotes the North Pole, the highest latitude on the globe.
3. Brazil, India, Japan, China
Ans: These are countries located in the Eastern and partly in the Northern Hemisphere (Brazil lies mostly in the Southern Hemisphere), used here as examples of countries situated at different latitudes and longitudes.
4. Moscow, Delhi, Sydney, Tokyo
Ans: These are major cities of the world located on different longitudes, and are commonly used as examples while explaining local time differences based on longitude.
Exercise C: Observing Figure No. 3.15 (One Hemisphere)
1. The figure 3.15 represents which hemisphere?
Ans: Figure 3.15 represents the Northern Hemisphere, since it shows the 60° North latitude circle.
2. How many circles are shown in the figure?
Ans: Two circles are shown in the figure — the outer circle (0°, the Equator) and the inner circle (60° North).
3. How many latitudes are shown in the figure?
Ans: Two latitudes are shown in the figure — 0° (the Equator) and 60° North.
4. How many longitudes are shown in the figure?
Ans: Four longitudes are shown in the figure, represented by the West-East and North-South cross lines passing through the centre of the circles.
5. Names of how many circles can be expressed for sure?
Ans: The names of two circles can be expressed for sure — the Equator (0°) and the 60° North latitude, since both are clearly labelled in the figure.
Exercise D: Difference Between Latitudes and Longitudes
D) Explain the difference between the latitudes and the longitudes with the help of a figure.
| Latitudes | Longitudes |
|---|---|
| Imaginary horizontal lines drawn parallel to the Equator. | Imaginary vertical lines drawn from the North Pole to the South Pole. |
| They are circles, and their length decreases from the Equator towards the poles. | They are semi-circles, and all longitudes are of equal length. |
| Consecutive latitudes are parallel to each other. | Consecutive longitudes are not parallel; they converge (meet) at the poles. |
| The 0° latitude is called the Equator. | The 0° longitude is called the Prime Meridian or base longitude. |
| Latitudes are used to determine how far north or south a place is. | Longitudes are used to determine how far east or west a place is, and to calculate local time. |
| The Equator divides the Earth into the Northern and Southern Hemispheres. | The 0° and 180° longitudes together divide the Earth into the Eastern and Western Hemispheres. |
Exercise E: Figure No. 3.16 – Fill in the Boxes
E) Choose the correct option and write the names of the main circles at their correct latitudes in Figure 3.16.
| Latitude Value | Name of the Circle |
|---|---|
| 66°30′ N | The Arctic Circle |
| 23°30′ N | The Tropic of Cancer |
| 0° | The Equator |
| 23°30′ S | The Tropic of Capricorn |
| 66°30′ S | The Antarctic Circle |
| 0° (vertical line) | The base longitude (Prime Meridian) |
Exercise F: Observing Figure No. 3.13
1. From which oceans and continents do all the longitudes pass?
Ans: All longitudes converge at the North Pole and the South Pole, so every longitude passes through the polar regions — the Arctic Ocean in the north and the continent of Antarctica in the south.
2. From which oceans and continents does the Equator pass?
Ans: The Equator passes through the continents of South America, Africa and Asia (through Indonesia), and through the Atlantic Ocean, Indian Ocean and Pacific Ocean.
3. From which continents and oceans does the prime meridian pass?
Ans: The Prime Meridian (0° longitude) passes through the continents of Europe (through the United Kingdom, France and Spain), Africa, and Antarctica, and through the Atlantic Ocean.
4. From which continents do both the 0° circles pass?
Ans: Both the 0° circles — the Equator and the Prime Meridian — pass through the continent of Africa.
5. How many latitudes on the globe are circular in shape?
Ans: All the latitudes on the globe are circular in shape, from the Equator up to the poles, though their size (diameter) keeps decreasing towards the poles.
Activity Notes (Pages 25-26)
Activity 1: Draw the graticule (network) of latitudes and longitudes on the circle given in the textbook to practise how latitude and longitude lines cross each other to form a grid on the globe.
Activity 2: ‘Eartha’ is the largest rotating globe in the world. Students are asked to gather additional information about ‘Eartha’ with the help of teachers and the internet, for classroom discussion.
Activity 2: ‘Eartha’ is the largest rotating globe in the world. Students are asked to gather additional information about ‘Eartha’ with the help of teachers and the internet, for classroom discussion.