Notes Class 8 Chapter 9 Geography Maharashtra Board

Notes For All Chapters – Geography Class 8

Map Scale

Introduction to Map Scale

• A map is a reduced representation of the earth or a part of it on a flat surface.
• It is not possible to represent real-world distances directly on paper; they need to be reduced in proportion.
• A map scale helps to represent these real-world distances in a manageable size.
• A map scale indicates the relationship between the distance on a map and the actual distance on the ground.

Example:

• If the scale of a map is 1 cm = 10 km, it means that 1 cm on the map represents 10 km in reality.

Why is a Map Scale Necessary?

1. Helps in measuring real-world distances accurately.
2. Assists in navigation and travel planning.
3. Enables comparison of distances between different locations.
4. Helps in understanding the size and shape of geographical features.
5. Ensures that maps can be drawn consistently for different purposes.

How a Map is Made

1. First, a survey is conducted to measure the actual distances on the ground.
2. A suitable scale is chosen based on the level of detail required.
3. The map is drawn according to this fixed scale.
4. After the map is completed, the scale is mentioned for easy reference.

Types of Map Scales

There are three main types of map scales used in cartography:

1. Verbal Scale (Statement Scale)

• The scale is expressed using words to describe the ratio between the map distance and ground distance.
• Example:“1 cm = 60 km” → 1 cm on the map equals 60 km on the ground.

Advantages:

• Easy to understand and use.
• Does not require any mathematical conversion.

Disadvantages:

• Difficult to use for accurate calculations.
• Becomes inaccurate if the map is resized.

2. Numerical Scale (Representative Fraction or RF)

• The scale is represented as a ratio between map distance and ground distance using the same unit.
• Example: 1 : 60,00,000 → 1 unit on the map represents 60,00,000 units on the ground.

Advantages:

• Can be easily converted into other units.
• Used worldwide, so it’s easy to compare different maps.

Disadvantages:

• No direct indication of units used.
• Requires calculation to interpret real distances.

Conversion Examples:

• 1 : 60,00,000 = 1 cm = 60 km
• 1 : 1,00,000 = 1 cm = 1 km

3. Linear Scale (Graphical Scale)

• A line or bar is drawn on the map, divided into equal segments representing real distances.
• You can measure distances directly using a ruler.

Advantages:

• Remains accurate even if the map is resized.
• Easy to use for measuring curved distances with string or thread.

Disadvantages:

• Requires a ruler or measuring tool.

Example: A linear scale divided into segments where:1 cm = 5 km0 cm → 5 km → 10 km → 15 km

Importance of Graphical Scale

• If a map is resized (enlarged or reduced), the graphical scale will adjust proportionally.
• Numerical and verbal scales may become inaccurate when the map size changes.
• That’s why graphical scales are commonly used in atlases and wall maps.

Large Scale and Small Scale Maps

1. Large Scale Maps

• Covers a small area with more detail.
• Generally used for city maps, village maps, and property maps.
• Scale is smaller than 1 : 10,000.

Examples:

• 1:5,000 → Large Scale
• 1:1,000 → Large Scale

2. Small Scale Maps

• Covers a large area with less detail.
• Used for country maps, world maps, and atlas maps.
• Scale is larger than 1 : 50,000.

Examples:

• 1:1,00,000 → Small Scale
• 1:10,00,000 → Small Scale

Measurement of Distances on a Map

1. Measure the distance between two points on the map using a ruler or string.
2. Refer to the scale on the map.
3. Convert the measured distance using the map scale.

Example:

• Scale: 1 cm = 10 km
• Distance on the map = 5 cmActual distance = 5 × 10 km = 50 km

Measuring Curved Distances

• Use a thread or piece of paper to trace the curve.
• Measure the length of the thread.
• Apply the map scale to find the actual distance.

Conversion of Scales

1. Verbal to Numerical Scale

Example: “1 cm = 53 km”

• Convert to numerical scale:1 cm / 53 km = 1 : 5,300,000

2. Numerical to Verbal Scale

Example: 1 : 10,000,000

• 1 cm on the map represents 100 km on the ground.

Use of Different Types of Scales