Chapter 6 – Satellite imageries and topographical maps

WBBSE Class 10 Geography Chapter 6 : Satellite imageries and topographical maps

Content Structure

1. Multiple choice questions and answers (MCQs)
2. Very short-type questions and answers
- 2A. Fill in the blanks
- 2B. True or false
- 2C. Very short-type questions and answers
3. Short-type questions and answers
4. Analytical questions and answers
5. Explanatory questions and answers

1. Multiple choice questions and answers (MCQs) [1 mark each]

1. Remote sensing refers to:
(a) Direct field survey
(b) Collection of data without contact
(c) Drawing maps
(d) Measuring temperature

Ans: (b) Collection of data without contact

2. The vertical distance between two contour lines is called:
(a) Scale
(b) Gradient
(c) Contour interval
(d) Spot height

Ans: (c) Contour interval

3. The main source of energy in remote sensing is:
(a) Moon
(b) Earth
(c) Sun
(d) Satellite

Ans: (c) Sun

4. Which sensor depends on sunlight?
(a) Active sensor
(b) Radar
(c) Passive sensor
(d) LiDAR

Ans: (c) Passive sensor

5. Which type of sensor uses its own energy?
(a) Passive sensor
(b) Active sensor
(c) Optical sensor
(d) Thermal sensor

Ans: (b) Active sensor

6. The point directly below a satellite is called:
(a) Zenith
(b) Nadir
(c) Horizon
(d) Orbit

Ans: (b) Nadir

7. The organization responsible for preparing topographical maps in India is:
(a) ISRO
(b) NASA
(c) Survey of India
(d) DRDO

Ans: (c) Survey of India

8. Contour lines join places of equal:
(a) Temperature
(b) Rainfall
(c) Elevation
(d) Distance

Ans: (c) Elevation

9. The headquarters of Survey of India is located in:
(a) Delhi
(b) Mumbai
(c) Dehradun
(d) Kolkata

Ans: (c) Dehradun

10. The scale 1:50,000 means:
(a) 1 cm = 50 km
(b) 1 cm = 500 m
(c) 1 cm = 50 m
(d) 1 cm = 5 km

Ans: (b) 1 cm = 500 m

11. The green colour on a toposheet indicates:
(a) Water bodies
(b) Vegetation
(c) Roads
(d) Settlements

Ans: (b) Vegetation

12. Million sheets have a scale of:
(a) 1:50,000
(b) 1:250,000
(c) 1:1,000,000
(d) 1:63,360

Ans: (c) 1:1,000,000

13. Closely spaced contour lines indicate:
(a) Gentle slope
(b) Steep slope
(c) Flat land
(d) Plateau

Ans: (b) Steep slope

14. Inch sheet maps have a scale of:
(a) 1:50,000
(b) 1:250,000
(c) 1:63,360
(d) 1:1,000,000

Ans: (c) 1:63,360

15. Degree sheets have a scale of:
(a) 1:50,000
(b) 1:250,000
(c) 1:1,000,000
(d) 1:63,360

Ans: (b) 1:250,000

2. Very short-type questions and answers

2A. True or false [1 mark each]

1. Active sensors depend on sunlight to capture images. (False)
2. The sky appears blue due to scattering of light. (True)
3. Contour lines join points of equal elevation. (True)
4. The Sun is the main source of energy in remote sensing. (True)
5. Widely spaced contour lines indicate a steep slope. (False)
6. Geo-stationary satellites are located near the poles. (False)
7. The green colour on a toposheet represents vegetation. (True)
8. Satellite images always show natural colours only. (False)
9. Geo-stationary satellites move faster than the Earth. (False)
10. FCC stands for False Colour Composite. (True)

2B. Fill in the Blanks [1 mark each]

1. The point directly below a satellite is called ________. (Nadir)
2. Degree sheets have a scale of ________. (1:250,000)
3. The main source of energy used in remote sensing is the ________. (Sun)
4. FCC stands for ________. (False Colour Composite)
5. Sensors that depend on sunlight are called ________ sensors. (Passive)
6. Geo-stationary satellites remain fixed over the ________. (Equator)
7. Lines joining equal heights on a map are called ________ lines. (Contour)
8. Vegetation on toposheets is shown in ________ colour. (Green)
9. Vegetation appears ________ in FCC images. (Red)
10. SPOT-1 was launched in the year ________. (1986)

2C. Very short-type questions and answers [1 mark each]

1. What is the metric scale of degree sheets of topographical maps?
Ans: The metric scale of degree sheets of topographical maps is 1:250,000.

2. What are the two methods of remote sensing?
Ans: The two methods of remote sensing are active remote sensing and passive remote sensing.

3. What are the basic steps of remote sensing?
Ans: The basic steps of remote sensing include the source of energy, transmission of energy through the atmosphere, interaction with the Earth’s surface, recording by sensors, and interpretation of data.

4. When was the term remote sensing first used?
Ans: The term remote sensing was first used in the year 1960.

5. What are topographical maps also shown in?
Ans: Topographical maps are also shown in the form of contour lines which represent the relief and elevation of the land.

6. What is the R.F. of topographical maps of the international series?
Ans: The representative fraction of topographical maps of the international series is 1:1,000,000.

7. Name the source of energy used in capturing satellite images?
Ans: The main source of energy used in capturing satellite images is the Sun.

8. How many grids of topographical maps are there in India?
Ans: There are about 56 grids of topographical maps in India in the international map series.

9. What is the scale of million sheets of Indian topographical maps?
Ans: The scale of million sheets of Indian topographical maps is 1:1,000,000.

10. What is the latitudinal and longitudinal extent of million sheets of Indian topographical maps?
Ans: The latitudinal and longitudinal extent of million sheets is 4° latitude and 6° longitude.

11. What kind of topographical map is map no. 73A?
Ans: Map number 73A is a degree sheet topographical map.

12. What is the latitudinal and longitudinal extent of degree sheets of Indian topographical maps?
Ans: The latitudinal and longitudinal extent of degree sheets of Indian topographical maps is 1° latitude and 1° longitude.

4. Analytical questions and answers [3 marks each]

1. What is remote sensing?
Ans: Remote sensing is the science of collecting information about the Earth’s surface without direct contact. It is done using sensors mounted on satellites or aircraft that detect and measure reflected or emitted energy from objects. This technique allows scientists to gather data about large and inaccessible areas efficiently. Remote sensing is widely used in agriculture, meteorology, geology, and environmental studies, making it an essential tool for understanding and managing natural resources.

2. What is nadir?
Ans: Nadir refers to the point on the Earth’s surface that lies directly below a satellite or an observer. In remote sensing, it is the exact point vertically beneath the sensor of a satellite. Images taken at the nadir position are usually the most accurate because they have minimal distortion compared to images taken at an angle. The concept of nadir is important in understanding how satellite images are captured and how their accuracy can vary depending on the viewing angle.

3. Who prepares the topographical maps in India?
Ans: Topographical maps in India are prepared by the Survey of India. It is the official government organization responsible for surveying and mapping the country. Established in 1767, it produces detailed and accurate maps that show natural and man-made features such as rivers, roads, hills, and settlements. These maps are widely used for planning, defense, education, and development purposes.

4. What are satellite images?
Ans: Satellite images are pictures of the Earth’s surface captured by sensors mounted on artificial satellites orbiting the Earth. These images provide valuable information about land, water, vegetation, and atmospheric conditions. They can be taken in different spectral bands, allowing scientists to study various features that are not visible to the human eye. Satellite images are widely used in weather forecasting, environmental monitoring, agriculture, and urban planning due to their ability to cover large areas quickly and accurately.

5. What are artificial satellites?
Ans: Artificial satellites are human-made objects that are launched into space and placed in orbit around the Earth or other celestial bodies. These satellites are designed for specific purposes such as communication, weather forecasting, navigation, and scientific research. They carry instruments and sensors that collect and transmit data back to Earth. Artificial satellites play a vital role in modern life, supporting technologies like television broadcasting, GPS, and disaster management systems.

6. What are geo-stationary satellites?
Ans: Geo-stationary satellites are satellites that orbit the Earth at a very high altitude of about 36,000 kilometers above the equator. They move at the same speed as the Earth’s rotation, which makes them appear stationary over a fixed point on the Earth’s surface. This allows them to continuously observe a particular area. These satellites are mainly used for communication, television broadcasting, and weather monitoring because they provide constant and real-time data.

4. Explanatory questions and answers [5 marks each]

1. Discuss the characteristic features of geo-stationary satellites.
Ans: Geo-stationary satellites are positioned in a circular orbit above the Earth’s equator at an altitude of about 36,000 kilometers. They revolve around the Earth at the same speed as the Earth’s rotation, which makes them appear stationary when viewed from the ground. This allows them to continuously monitor a specific area without interruption. These satellites are mainly used for communication, television broadcasting, and weather forecasting. They can cover a large portion of the Earth’s surface and provide real-time data. However, they are not suitable for detailed mapping due to their high altitude. An example of such satellites includes the INSAT system.

2. What is meant by an inch to a mile toposheet?
Ans: An inch to a mile toposheet refers to a specific map scale where one inch on the map represents one mile on the ground. This scale is commonly expressed as 1:63,360 and is widely used in topographical mapping. It helps in accurately measuring distances and understanding spatial relationships between features. Such toposheets provide a detailed representation of both natural and cultural features of an area. They are particularly useful for navigation, planning, and surveying purposes. The scale ensures that users can easily convert map distances into real-world distances, making it highly practical for geographers, engineers, and travelers.

3. What is LANDSAT series satellites?
Ans: The LANDSAT program is a series of Earth observation satellites launched by the United States to study the Earth’s surface. Since its first launch in 1972, the program has provided continuous and valuable data about land use, vegetation, water bodies, and environmental changes. These satellites use multi-spectral sensors to capture images in different wavelengths, which helps scientists analyze various physical features of the Earth. LANDSAT data is widely used in agriculture, forestry, geology, urban planning, and disaster management. It plays an important role in monitoring environmental changes such as deforestation, desertification, and climate change, making it one of the most important remote sensing programs in the world.

4. Write some characteristics of topographical maps.
Ans:

Detailed representation: Topographical maps provide a detailed and accurate representation of the Earth’s surface, showing both natural and man-made features.
Use of contour lines: Topographical maps use contour lines to represent elevation and relief, helping to understand the shape and height of the land.
Inclusion of features: Topographical maps show features such as rivers, hills, roads, buildings, forests, and settlements clearly.
Scale and direction: Topographical maps are drawn to a specific scale and include directions, usually indicated by a north arrow.
Use of symbols: Topographical maps use standard symbols and conventional signs to represent different physical and cultural features.
Accuracy and reliability: Topographical maps are prepared through detailed ground surveys, making them highly accurate and reliable.
Wide usage: Topographical maps are used in military operations, urban planning, geographical studies, and educational purposes.

5. Discuss the characteristic features of sun-synchronous satellites.
Ans: Sun-synchronous satellites are a special type of polar orbiting satellites that pass over the same part of the Earth at the same local time every day. This unique feature ensures that the lighting conditions remain consistent for every observation, making it easier to compare images over time. These satellites move from pole to pole and gradually cover the entire Earth as the planet rotates beneath them. They operate at relatively low altitudes and are widely used in remote sensing and Earth observation. Because of their consistent lighting and repeated coverage, they are highly useful in environmental monitoring, mapping, and studying seasonal changes. Their ability to provide uniform and reliable data makes them essential for scientific research and resource management.

6. Discuss the use of colours in developing satellite images.
Ans: Colours play a vital role in the interpretation of satellite images, as they help distinguish different features of the Earth’s surface. In true-colour images, natural colours are used, where water appears blue, vegetation appears green, and barren land appears brown. However, in many cases, false colours are used to enhance specific features that are not easily visible in natural colours. For example, vegetation may appear red in false-colour images to highlight its health and density. Different colours represent different wavelengths of light captured by sensors. This colour coding makes it easier for scientists and researchers to analyze land use, vegetation cover, water bodies, and environmental changes. Thus, the use of colours greatly improves the clarity and usefulness of satellite images.