Chapter 1 · Topic 1.2 · Prelims + Mains2 of 3
Fundamentals of Geography: Location, time and maps
Key points
- Latitude and longitude; Tropic of Cancer crosses eight States; equator misses Tanganyika,
- 15° = 1 hour; IST at 82°30′ E; countries with more than four time zones (2025); Date Line rules.
- Large scale means small area; Mercator, conical and zenithal projections.
Prelims box: facts and traps
| Projection | Good for |
|---|---|
| Cylindrical (Mercator) | Navigation, because directions are true |
| Conical | Mid-latitude countries |
| Zenithal (azimuthal) | Polar regions, air routes. |
- Indian Standard Time is set by 82°30′ E, which passes near Mirzapur in Uttar Pradesh; it is 5 h 30 min ahead of Greenwich.
- The Survey of India, founded in 1767, is the national mapping agency.
- India's Standard Meridian is 82°30'E. Since the Earth turns 15° in one hour (1° in 4 minutes), 82.5° corresponds to 82.5 × 4 = 330 minutes, that is 5 hours 30 minutes.
- Trap: The two places lie on opposite sides of the Prime Meridian, so the longitude difference is 75 + 45 = 120°.
Latitude, longitude, time zones and the Date Line
Latitude is the angle north or south of the equator (0° to 90°); one degree of latitude is about 111 km. Key parallels: the Tropic of Cancer (23.5° N), the Tropic of Capricorn (23.5° S), the Arctic and Antarctic Circles (66.5°). The Tropic of Cancer crosses eight Indian States: Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura and Mizoram. Longitude is the angle east or west of the Prime Meridian at Greenwich. The Earth turns 360° in 24 hours: 15° per hour, or 4 minutes per degree.
Map-reading questions are common. Prelims 2025 named Lake Tanganyika, Lake Tonlé Sap and Patos Lagoon and asked: Through how many of them does the equator pass? Prelims 2025 None (option d): Tanganyika lies wholly south of the equator, Tonlé Sap is in Cambodia, and Patos Lagoon is in southern Brazil. The equator does cross Lake Victoria.
Consider the following water bodies : I. Lake Tanganyika II. Lake Tonlé Sap III. Patos Lagoon Through how many of them does the equator pass?
- Only one
- Only two
- All the three
- None
Show answer
Answer: (d) · UPSC official key
Indian Standard Time is set by 82°30′ E, which passes near Mirzapur in Uttar Pradesh; it is 5 h 30 min ahead of Greenwich. India spans about 30° of longitude, so the Sun rises roughly two hours earlier in Arunachal Pradesh than in western Gujarat. Large countries use several zones, and overseas territories add more. Prelims 2025 asked which of the UK, Denmark, New Zealand, Australia and Brazil have more than four time zones: four of them (option b), all except Brazil, which has four. The International Date Line runs roughly along 180° but bends around island groups. Crossing it westward, you add a day; crossing eastward, you drop one.
Consider the following countries : I. United Kingdom II. Denmark III. New Zealand IV. Australia V. Brazil How many of the above countries have more than four time zones?
- All the five
- Only four
- Only three
- Only two
Show answer
Answer: (b) · UPSC official key
Maps, scale and projections
A map shows the curved Earth on a flat sheet, to scale. Scale can be written in words (1 cm to 1 km), as a ratio or representative fraction (1:100,000), or as a drawn bar (graphic scale). The trap: a large-scale map (1:50,000) shows a small area in great detail, such as the Survey of India’s topographical sheets; a small-scale map (1:10,000,000) shows a large area with little detail, such as an atlas map of the world.
| Projection | Good for | Distortion |
|---|---|---|
| Cylindrical (Mercator) | Navigation, because directions are true | Areas swell towards the poles; Greenland looks as big as Africa |
| Conical | Mid-latitude countries | Grows away from the standard parallel |
| Zenithal (azimuthal) | Polar regions, air routes | Grows away from the centre point |
No flat map can keep area, shape, distance and direction all correct at once; each projection chooses what to keep. The Survey of India, founded in 1767, is the national mapping agency.
Mains box: analysis and answer points
- Latitude is the angle north or south of the equator (0° to 90°); one degree of latitude is about 111 km.
- Key parallels: the Tropic of Cancer (23.5° N), the Tropic of Capricorn (23.5° S), the Arctic and Antarctic Circles (66.5°).
- The Tropic of Cancer crosses eight Indian States: Gujarat, Rajasthan, Madhya Pradesh, Chhattisgarh, Jharkhand, West Bengal, Tripura and Mizoram.
- Likely next angle: Lines through lakes, straits and countries
Practice
Practice MCQs (8)
Consider the following statements: Statement-I: The Sun rises in Arunachal Pradesh nearly two hours earlier than in western Gujarat, yet clocks in both States show the same time. Statement-II: India extends across nearly 30° of longitude but follows a single standard meridian for the whole country.
Answer (a) & explanation
Both statements are correct and Statement-II explains Statement-I. Mainland India stretches from 68°7'E to 97°25'E, nearly 30° of longitude. At 4 minutes per degree this gives a time lag of about two hours between Gujarat and Arunachal Pradesh, which is why the Sun rises much earlier in the east. Because the whole country follows one Standard Meridian (82°30'E), clocks everywhere show the same time.
When it is 12 noon at Greenwich (0°), the Indian Standard Time is
Answer (d) & explanation
India's Standard Meridian is 82°30'E. Since the Earth turns 15° in one hour (1° in 4 minutes), 82.5° corresponds to 82.5 × 4 = 330 minutes, that is 5 hours 30 minutes. India lies east of Greenwich, so its time is ahead: 12 noon + 5:30 = 5:30 PM.
Consider the following statements regarding the choice of 82°30'E as the Standard Meridian of India:
1. It lies close to the middle of India's longitudinal extent, so neither end of the country is much more than an hour away from standard time.
2. Being a multiple of 7°30', it keeps Indian Standard Time a whole number of half-hours away from Greenwich time.
3. It is the meridian passing through the national capital, New Delhi.
Which of the statements given above is/are correct?
Answer (b) & explanation
Statements 1 and 2 are correct. Mainland India spans 68°7'E to 97°25'E; 82°30'E lies near the middle, so the western and eastern extremities are each only about an hour off standard time. Countries usually choose standard meridians in multiples of 7°30', which equal 30 minutes of time; 82°30' = 11 × 7°30', giving IST = GMT + 5:30. New Delhi lies at about 77°E, well west of the Standard Meridian, which passes near Mirzapur in Uttar Pradesh.
When it is 12 noon local time at a place on 75°E longitude, what is the local time at a place on 45°W longitude?
Answer (a) & explanation
The two places lie on opposite sides of the Prime Meridian, so the longitude difference is 75 + 45 = 120°. At 4 minutes per degree, 120° = 480 minutes = 8 hours. The place at 45°W is to the west, so it is behind: 12 noon − 8 hours = 4:00 AM.
Which one of the following statements about meridians of longitude is NOT correct?
Answer (d) & explanation
Meridians are semicircles joining the two poles, so they are all of equal length. They are numbered from the Prime Meridian (0°) up to 180° eastwards and westwards; 180°E and 180°W are the same line, lying opposite the Prime Meridian. It is parallels of latitude that are numbered from 0° to 90° north and south.
Consider the following statements about the International Date Line:
1. A traveller crossing the Date Line eastwards, from Asia towards America, sets the calendar back by one day.
2. The Date Line follows the 180° meridian exactly along its whole length.
3. Places lying just west of the Date Line are among the first on the Earth to begin a new calendar day.
Which of the statements given above are correct?
Answer (d) & explanation
Statements 1 and 3 are correct. Places west of the International Date Line are a full day ahead of places just east of it. So a traveller going eastwards (Asia to America) repeats a date, setting the calendar back by one day; going westwards, a day is skipped. Places just west of the line, such as Kiribati's Line Islands, are the first to greet a new day. The line zigzags away from the 180° meridian to avoid dividing island groups and countries (for example, around Kiribati and between Siberia and Alaska).
The local time at a place is 4 hours 40 minutes ahead of the local time at Greenwich. The longitude of the place is
Answer (c) & explanation
The Earth turns 1° of longitude in 4 minutes. A difference of 4 h 40 min = 280 minutes therefore corresponds to 280 ÷ 4 = 70° of longitude. Since the place is ahead of Greenwich, it lies to the east: 70°E.
Consider the following States:
1. Uttar Pradesh
2. Madhya Pradesh
3. Chhattisgarh
4. Telangana
5. Odisha
6. Jharkhand Through how many of the above States does the 82°30'E meridian pass?
Answer (b) & explanation
The 82°30'E meridian runs north to south through Uttar Pradesh, Madhya Pradesh, Chhattisgarh, Odisha and Andhra Pradesh, meeting the Bay of Bengal near Kakinada. From the list, four States lie on it: UP, MP, Chhattisgarh and Odisha. Telangana lies wholly west of it (its eastern edge stops short of 82°E), and Jharkhand lies wholly east of it.
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In 150 words, explain the significance of Fundamentals of Geography with one recent example.
Flashcards (9)
How many km in one degree of latitude?
About 111 km.
How many Indian States does the Tropic of
Cancer cross? Eight.
Longitude of IST?
82°30′ E (near Mirzapur).
Minutes of time per degree of longitude?
Four.
Does the equator pass through Lake
Tanganyika? No; it crosses Lake Victoria.
Crossing the Date Line westward: add or
drop a day? Add a day.
Large-scale map: large or small area?
Small area, more detail.
What does the Mercator projection keep
true? Direction (shape locally).
Which projection suits polar regions?
Zenithal (azimuthal).
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