NCERT Class 11 Geography Pratical Work in Geography: Chapter 6 — Introduction To Remote Sensing
This chapter introduces the concept of Remote Sensing, a technique used to acquire information about objects and phenomena without physical contact. It explains that while human eyes and photographic systems respond to visible light, modern remote sensing devices can detect a wider range of electromagnetic radiation (EMR) reflected or emitted by surfaces. The chapter defines remote sensing as the process involving an object's surface, a recording device (sensor), and information-carrying energy waves. It highlights the importance of understanding EMR and its interaction with surfaces for data acquisition. The chapter also includes a glossary of key terms such as Absorptance, Band, Digital image, Electromagnetic Spectrum, and Sensor, crucial for comprehending remote sensing principles in Geography practical work for CBSE students.
Quick info
| Board | CBSE / NCERT |
|---|---|
| Class | Class 11 |
| Subject | Geography |
| Book | Pratical Work in Geography |
| Chapter | Chapter 6 — Introduction To Remote Sensing |
| Language | English |
| PDF type | NCERT Textbook |
| Session | CBSE 2026 |
| Reading time | 2 minutes |
| Word count | 345 |
Learning outcomes
- Define remote sensing and its fundamental components.
- Differentiate between human vision and remote sensing devices in detecting radiation.
- Understand the role of energy waves in transmitting information.
- Identify key terms related to remote sensing principles.
Vocabulary
| Word | Meaning |
|---|---|
| Remote Sensing | The process of acquiring information about an object or phenomenon without physical contact, using sensors that detect reflected or emitted energy. |
| Sensor | A device that receives electromagnetic radiation (EMR) and converts it into a signal for recording. |
| Electromagnetic Radiation (EMR) | Energy propagated through space at the speed of light, encompassing a wide spectrum of wavelengths. |
| Electromagnetic Spectrum | The continuum of EMR ranging from cosmic rays to radio waves. |
| Band | A specific interval of wavelengths within the electromagnetic spectrum. |
| Digital image | An array of digital numbers representing intensity values and locations of pixels. |
| Absorptance | The ratio of absorbed radiant energy to the total energy received by a substance. |
| Reflectance | The ratio of reflected radiant energy to the total energy received by a substance. |
| False Colour Composite (FCC) | An artificially generated colour image where colours are assigned to wavelength regions not corresponding to their natural appearance. |
| Digital Number (DN) | An intensity value assigned to a pixel in a digital image. |
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Practice questions
- What is the fundamental difference between how human eyes and remote sensing devices perceive the environment? Answer: Human eyes primarily respond to visible light, while remote sensing devices can detect a much wider range of electromagnetic radiation, including infrared and microwave.
- Define remote sensing based on the provided text. Answer: Remote sensing is defined as the total process used to acquire and measure information about the properties of objects and phenomena by a recording device (sensor) that is not in physical contact with them.
- What are the three primary components involved in remote sensing? Answer: The three primary components are the object surface, the recording device (sensor), and the information-carrying energy waves.
Practice MCQs
Q1. Remote sensing devices can react to a wider range of radiations than human eyes, including those emitted or reflected by objects at temperatures above:
Explanation: The text states that remote sensing devices react to radiations from objects at a temperature above 0 Kelvin (-273°C), unlike human eyes which are limited to visible light.
Q2. The term 'remote sensing' was first used in which decade?
Explanation: According to the text, the term 'remote sensing' was first used in the early 1960s.
Q3. Which of the following is NOT a primary component involved in remote sensing as defined in the chapter?
Explanation: The chapter explicitly mentions the object surface, the recording device (sensor), and the information-carrying energy waves as the primary components of remote sensing.
Q4. What does 'Absorptance' refer to in the context of remote sensing?
Explanation: The glossary defines Absorptance as the ratio of the radiant energy absorbed by a substance to the energy it receives.
Q5. A 'Band' in remote sensing refers to:
Explanation: The glossary defines a 'Band' as a specific wavelength interval in the electromagnetic spectrum.
Frequently asked questions
What is remote sensing?
Remote sensing is the process of acquiring information about an object or phenomenon without being in physical contact with it, using sensors that detect energy waves.
How does remote sensing differ from human vision?
Human vision is limited to the visible light spectrum, whereas remote sensing devices can detect a much broader range of electromagnetic radiation, including infrared and microwave.
What are the essential elements of remote sensing?
The essential elements are the object's surface, the sensor (recording device), and the information-carrying energy waves.
What is an electromagnetic spectrum?
The electromagnetic spectrum is the entire range of electromagnetic radiation, from short-wave cosmic rays to long-wave radio waves.
What is a 'band' in the context of remote sensing?
A band refers to a specific interval of wavelengths within the electromagnetic spectrum used for data collection.
What is the purpose of a sensor in remote sensing?
A sensor receives electromagnetic radiation from the Earth's surface and converts it into a signal that can be recorded and processed into an image.
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NCERT Class 11 Geography — Pratical Work in Geography — Chapter 6 — Introduction To Remote Sensing. Verified by NCERT Help Editorial Team. Reviewed on 29 Jul 2026. Last updated 10 Aug 2026.