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Class 11 Geography (Book – Practical Work in Geography ) Chapter – 6 (Introduction to Remote Sensing) focuses on the fundamental concepts and applications of remote sensing technology. The chapter defines remote sensing and explains how it works to gather information about Earth’s surface from a distance typically using sensors on satellites or aircraft.
In this article, you will get the NCERT class 11 Geography Chapter 6 – Introduction to Remote Sensing Exercise Questions with Answers.
NCERT Solutions Class 11 Geography Practical Chapter 6: Introduction to Remote Sensing
1. Choose the right answer from the four alternatives given below :
(i) Remote sensing of objects can be done through various means such as A. remote sensors, B. human eyes, and C. photographic system. Which of the following represents the true order of their evolution?
(a) ABC
(b) BCA
(c) CAB
(d) None of the above
(b) BCA
Explanation – Remote Sensing of objects was done through the human eyes, through the photographic systems respond to light in a minute portion of the total energy received and responded by the objects surface. Then by recording device (sensor), that is not in physical contact with the objects .
(ii) Which of the following regions of the Electromagnetic spectrum is not used in satellite remote sensing?
(a) Microwave region
(b) Infrared region
(c) X – rays
(d) Visible region
(c) X – rays
Explanation – On the basis of the size of the waves and frequency, the energy waves are grouped into gamma, X rays, Ultravoilet rays, Visible rays, Infrared rays, Microwaves and Radio waves. In satellite remote sensing the Multi Spectral Scanners (MSS) are used as sensors. The visible infrared and microwave regions of energy are used in remote sensing.
(iii) Which of the following is not used in visual interpretation techniques?
(a) Spatial arrangements of objects
(b) Frequency of tonal change on the image
(c) Location of objects concerning the other objects
(d) Digital image processing
Answer:
(a) Spatial arrangements of objects
Explanation- The visual interpretation is a manual exercise. It involves reading the image of objects for the purpose of their identification .Spatial arrangement of many natural and man-made features show the repetitive appearance of forms and relationship. The arrangement can easily be identified from the images through the utilization of the pattern they form.
2. Answer the following questions in about 30 words.
(i) Why is remote sensing a better technique than other traditional methods?
Remote sensing is a better techique than other traditional methods because:
- It represents a consise picture of a large area.
- It provide real or nearly real pictures on time baseline.
- It is less expensive as compared to land survey and we can easily collect informatio by using it.
- It coverts energy received into the photographic /digital form of data.
- It is not affected by bad weather and inaccessible land.
(ii) Differentiate between the IRS and INSAT series of satellites.
IRS (Indian Remote Sensing): These satellites are designed for Earth observation. They carry various sensors to capture high-resolution images of the Earth’s surface. Applications include monitoring land use, forestry, agriculture, and natural disasters. IRS are remote sensing satellite which the sensors recording the energy that they receive are placed in a near ploar sun synchronous orbit at an altitude of 700-900km .IRS is the largest civilian remote sensing satellite constellation in the world .
INSAT (Indian National Satellite System): This is a series of multipurpose communication satellites. INSAT satellites provide services like telecommunication, television broadcasting, weather forecasting, and disaster warning.Its orbit synchronises with the diirection of the rotation of earth. They are positioned aginst the remote sensing satelllite and revolve around at an altitude of nearly 36,000 km .These are weather monitoring and telecommunication satellites .INSAT is one of the largest domestic communication satellite sysytem in the Asia-Pacific region.
IRS: These satellites typically occupy Sun-synchronous orbits. This means they pass over the same spot on Earth at roughly the same time each day, under similar lighting conditions. This is important for consistent image capture.
INSAT: INSAT satellites are placed in geostationary orbits. This means they appear stationary from the Earth’s surface, as their orbital period matches the Earth’s rotation. This is ideal for communication applications.
Applications:
IRS: Data from IRS satellites is used in various fields, including:
- Resource management: Monitoring forests, water resources, and mineral deposits.
- Disaster management: Assessing damage caused by floods, earthquakes, and other natural disasters.
- Urban planning: Monitoring urban growth and land use patterns.
- Agriculture: Crop yield estimation and monitoring soil health.
INSAT: INSAT satellites provide a wide range of communication services, including:
- Telephony: Long-distance telephone calls within India.
- Television broadcasting: Delivering TV signals to homes across the country.
- Radio broadcasting: Providing radio services for education and entertainment.
- Meteorology: Providing data for weather forecasting.
- Disaster warning: Disseminating early warnings for cyclones, floods, and other natural disasters.
In short, IRS satellites are for observing the Earth, while INSAT satellites are for communication purposes. They utilize different orbits to best suit their specific functions.
(iii) Describe in brief the functioning of the push broom scanner.
Answer:
A push broom scanner also known as an along-track scanner works like a sweeping broom that gathers information as it moves. Here’s a breakdown of its operation:
Sensor Array:
Imagine a line of tiny detectors arranged side-by-side. This linear array acts like the bristles of the broom.
Scanning Motion:
The scanner moves forward, much like how you sweep a broom. This motion can be on a satellite orbiting Earth or a sensor mounted on a platform moving over a surface.
Data Collection:
As the scanner moves, each detector captures data from a small strip of the area being scanned. Think of each detector like a single bristle picking up dirt.
Building the Image:
By continuously collecting data from all the detectors and stitching it together, a complete image is gradually built line by line.
Analogy:
Imagine a long piece of paper where you slowly draw a line across it with a pen. The pen leaves a trail of data like a single detector. If you move the paper continuously while making multiple parallel lines with the pen, you essentially replicate how a push broom scanner builds an image.
Additional Points:
- Push broom scanners can be used in various applications, including remote sensing from satellites and spectral analysis in industrial settings.
- Compared to other scanners, push broom scanners can gather more light due to their longer observation time per area.
Q3. Answer the following questions in about 125 words.
(i) Describe the operation of a whiskbroom scanner with the help of a diagram. Explain how it is different from the push broom scanner.
Answer:
Both whiskbroom and pushbroom scanners are imaging devices used in remote sensing applications, but they achieve image capture in fundamentally different ways. Here’s a breakdown with a diagram:
Whiskbroom Scanner:
Components:
- A single detector
- A rotating mirror
Operation (refer to diagram):
- The rotating mirror sweeps back and forth, similar to a whisk being used to sweep dust.
- Light from the area of interest reflects off the ground and is captured by the mirror at different angles as it rotates.
- The mirror directs the collected light onto the single detector.
- The detector measures the intensity of the light at each point in the scan.
- By continuously rotating and measuring, the scanner builds up an image one pixel at a time.
Diagram: |—————–|
|—DETECTOR—| (Single )
/\ /\ (Rotating Mirror)
/ \ / \ (Light Path)
/——– \/———\
Ground
Pushbroom Scanner (refer to previous explanation for details):
- Uses a linear array of detectors (multiple detectors) that capture data simultaneously.
- Scans by moving the entire sensor forward (like a push broom) instead of having a rotating mirror.
Key Differences:
- Number of Detectors: Whiskbroom – Single, Pushbroom – Linear Array (Multiple)
- Scanning Mechanism: Whiskbroom – Rotating Mirror, Pushbroom – Sensor Movement
- Data Acquisition: Whiskbroom – Pixel by Pixel, Pushbroom – Line by Line (Simultaneous)
- Image Build-up: Whiskbroom – Slower, one pixel at a time, Pushbroom – Faster, line by line
Advantages of Pushbroom Scanners:
- Faster image acquisition
- More sensitive due to longer observation time per area
- Simpler design (no moving parts)
Advantages of Whiskbroom Scanners:
- Easier to calibrate (only one detector)
- Can potentially capture a wider field of view (depending on mirror design)
In conclusion, both scanners have their pros and cons. Pushbroom scanners are generally preferred due to their speed and sensitivity, while whiskbroom scanners may be used in specific applications where wider field of view or simpler calibration is crucial.
(ii) Identify and list the changes that can be observed in the vegetation of the Himalayas.
Answer:
The himalayan ranges show a sucession of vegetation from the tropical of tundra with a change in altitude .Deciduous forests are found in the fooothills of the himalayas .It is succceeded by the west temperature types of forests between an altitude of 1,000-2,000.
After 3000 metre altitude , conical forests are found whhich have sharp leaves .Important trees in this region are Chid,Phir,Pine,Spurs etc.The red patches in May image refers to Corniferous Vegetation .In November image the additional red patches refer to decidious plants and the light red colour is related to the crops .
The vegetation of the Himalayas is undergoing several changes due to various factors.
- Shifting of vegetation zones: As temperatures rise due to climate change there’s a trend of vegetation zones moving uphill. This means areas that were once covered by certain plants at lower altitudes are now becoming suitable for those plants at higher altitudes.
- Tree line creep: The tree line which is the boundary between the treeless zone and the forested zone is moving upwards. This indicates that trees are establishing themselves at higher elevations than before.
- Changes in species composition: The types of plants found in specific areas are changing. Some species adapted to colder temperatures may struggle as it gets warmer, while species suited to warmer climates may move in.
- Loss of alpine meadows: As tree lines creep upwards alpine meadows (grasslands at high altitudes) are shrinking. This can affect grazing areas for animals and biodiversity.
- Impact on biodiversity: Changes in vegetation affect the entire ecosystem. Animals that depend on specific plants for food or habitat may be impacted by these shifts.
These are some of the significant changes observed in the vegetation of the Himalayas. It’s important to note that these changes can vary depending on the specific location and other environmental factors.
NCERT Geography Class 11 Chapter 6 (Introduction to Remote Sensing) Chapter Summary
This chapter explores how remote sensing technology helps us gather information about Earth from a distance.
- What is Remote Sensing? It’s a technique using sensors on satellites or aircraft to collect data without physically being there.
- How Does it Work? Sensors detect electromagnetic radiation (light) reflecting off the Earth’s surface revealing details about land, water and vegetation.
- Types of Remote Sensing: Satellites offer a broad view, while aerial photography provides high-resolution close-ups.
- Applications: Remote sensing is used for resource management (forests, water) disaster management, urban planning, agriculture (crop yield, soil health) and environmental monitoring.
- Understanding the Data: “Image interpretation” involves analyzing data based on colour, texture, and patterns to extract information.
- Advantages: Remote sensing offers a large-scale view and allows tracking changes over time.
- Limitations: Weather conditions and complex data processing can be challenging. The chapter also acknowledges limitations like dependence on weather conditions high data processing needs, and potential cost implications.
By studying remote sensing students gain an understanding of a powerful tool used in various geographical studies and real-world applications. This chapter helps students with a foundational understanding of this critical technology and its role in geographical studies and various real-world applications.
Important Topics discussed in Class 11 Geography Chapter 6: Intro to Remote Sensing
Also Check:
NCERT Solutions Class 11 Geography Practical Chapter 6: Introduction to Remote Sensing – FAQs
What is remote sensing in geography class 11?
Remote sensing is the process of detecting and monitoring the physical characteristics of an area by measuring its reflected and emitted radiation at a distance (typically from satellite or aircraft).
What is called aerial photography?
An aerial photograph, in broad terms, is any photograph taken from the air. Normally, air photos are taken vertically from an aircraft using a highly-accurate camera.
In which city were the first aerial photographs taken?
Aerial photography was first practiced by the French photographer and balloonist Gaspard-Félix Tournachon known as “Nadar” in 1858 over Paris France. However the photographs he produced no longer exist and therefore the earliest surviving aerial photograph is titled ‘Boston as the Eagle and the Wild Goose See It.
Who is the father of aerial photography?
Talbert “Ted” Abrams (August 17, 1895 – August 25, 1990) was an American photographer and aviator known as the “father of aerial photography”.
What does GIS stand for?
GIS stands for geographic information systems are computer-based tools used to store, visualize, analyze, and interpret geographic data. Geographic data (also called spatial or geospatial data) identifies the geographic location of features.
Is GPS a GIS?
Global Positioning Systems or GPS are used to find the exact location of things. Geographic Information Systems or GIS are used to record information on to maps.
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