📚 World Geography – Study Notes for IIT‑JEE / Competitive Exams
Target Audience: Students preparing for IIT‑JEE, JEE Advanced, NEET‑UG, AIIMS, and other competitive exams where General Awareness & Current Affairs is part of the syllabus.
Objective: Master the core concepts, memorize critical facts, and be ready to tackle any geography‑based question, including data‑interpretation, map‑reading, and current‑affairs‑related problems.
1. Core Concepts & Taxonomy
| Category | Key Points | Why it matters |
|---|---|---|
| Continents & Oceans | 7 continents, 5 oceans | Geography’s backbone; many exam questions revolve around size, region, and characteristics. |
| Latitude / Longitude | 0° to 90°N/S, 0° to 180°E/W | Needed for coordinate‑based calculations (distance, area). |
| Tectonic Plates | Pacific, Eurasian, African, North American, South American, Indo‑Australian, Antarctic | Determines mountain ranges, earthquakes, and volcanic activity. |
| Major River Systems | Nile, Amazon, Yangtze, Mississippi, Ganges‑Brahmaputra | Often used in data‑interpretation questions. |
| Climate Zones | Tropical, Subtropical, Temperate, Polar | Impacts agriculture, population density, and disaster risk. |
| Population & Area | Size, density, growth | Frequently combined with economic data. |
| Current Affairs | New countries, territorial disputes, climate accords | Keeps knowledge up‑to‑date for the “Current Affairs” section. |
2. Geographical Coordinate System
| Concept | Formula / Value | Example |
|---|---|---|
| Latitude | ( \varphi \in [-90°, 90°] ) | ( \varphi = 28.6139°,N ) (Delhi) |
| Longitude | ( \lambda \in [-180°, 180°] ) | ( \lambda = 77.2090°,E ) (Delhi) |
| Conversion to metres | 1° latitude ≈ 111 km (constant) 1° longitude ≈ 111 km × cos(latitude) |
At 60° N, 1° lon ≈ 55 km |
| Great‑Circle Distance (Haversine) | [ | |
| d = 2R \arcsin!\left(\sqrt{h}\right), \quad h = \sin^2!\frac{\Delta\varphi}{2} + \cos\varphi_1\cos\varphi_2\sin^2!\frac{\Delta\lambda}{2} | ||
| ] | (R = 6371,\text{km}). Distance between Delhi & Mumbai ≈ 201 km. |
Tricky Point: Do not use the “12 km per minute” rule for longitude at high latitudes; it over‑estimates distance.