हिंदी
CISCEISC (Arts) Class 12
प्रश्न पत्र३७२
पाठ्यपुस्तक उत्तर१६६८१
महत्वपूर्ण प्रश्न एवं उत्तर५८७१
अवधारणा स्पष्टीकरण और वीडियो९५३
समय सारणी१५
पाठ्यक्रम

Overview of Remote Sensing

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Estimated time: 22 minutes
CISCE: Class 12

Key Points: Introduction of Remote Sensing

  • Meaning of Remote Sensing: It is the process of collecting information about objects or areas from a distance, without direct contact.
  • Basis of Remote Sensing: It works by detecting reflected or emitted electromagnetic energy from objects.
  • Natural & Artificial Sensors: Human senses act as natural sensors, but special instruments are used as remote sensors.
  • Types of Remote Sensors: Main instruments are Radiometer, Audiometer, Magnetometer and Gravimeter.
  • Uses: These instruments measure radiation, sound waves, magnetic field and gravity to study earth features, ocean floor and natural resources.
CISCE: Class 12

Key Points: Electromagnetic Spectrum and Energy

  • Electromagnetic Radiation: It is a form of energy that travels in waves at the speed of light.
  • Wavelength & Frequency: Long wavelength = low frequency; short wavelength = high frequency (measured in hertz).
  • Electromagnetic Spectrum: Includes gamma rays, X-rays, ultraviolet, visible light, infrared, microwaves and radio waves.
  • Visible Spectrum: Ranges from about 0.4 to 0.7 microns (violet to red); only a small part of the total spectrum.
  • Electromagnetic Energy Principle: All objects above 0 K emit energy; hotter objects emit more energy and shorter wavelengths.
  • Sensing Systems:
    Passive system uses natural energy (e.g., camera).
    Active system sends its own energy (e.g., radar).
  • Effects of Atmosphere: Gases and dust absorb and scatter radiation; certain “windows” allow energy to pass for remote sensing.
CISCE: Class 12

Key Points: Zones of Remote Sensing

  • Gamma Ray Region: Used to detect radioactive minerals like uranium, thorium and potassium for geological studies.
  • Ultraviolet Region: Helps in identifying minerals, soils and water bodies; useful in mineral and ocean studies.
  • Visible Region: Most commonly used in remote sensing; uses cameras and scanners on aircraft and satellites.
  • Infrared Region: Detects thermal energy; useful in studying forest fires, crop health, soil moisture and geological features.
  • Multispectral Remote Sensing: Uses multiple spectral bands to get detailed and accurate information about land, soil and vegetation.
  • Microwave Region (Radar): Works in all weather and day-night conditions; can penetrate clouds and haze.
  • Radar/SLAR Imaging: Produces sharp images of terrain; useful for mapping landforms and surface features.
CISCE: Class 12

Key Points: Photography

  • Aerial Photography: It was the first remote sensing method used to collect geographical information about the earth.
  • Historical Development: First aerial photographs were taken in 1909; its importance increased during World Wars.
  • False Colour Photography: Developed during World War II; helps to distinguish vegetation, crops, water pollution and land use.
  • Scale of Aerial Photograph: Scale depends on camera focal length and height of the camera above ground.
CISCE: Class 12

Formula: Representative Fraction (R.F.)

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CISCE: Class 12

Key Points: Remote Sensing from Spacecrafts

  • Remote Sensing from Spacecraft: Satellites take photographs and collect data from space, covering very large areas.
  • Advantages: Greater perspective, wide (synoptic) coverage and rapid repetitive coverage of the earth.
  • Types of Sensors: Both active and passive sensors are used on satellites.
  • Important Satellites:
    TIROS (1960) – weather observation
    LANDSAT (from 1972) – earth resource study
    ERS – radar and microwave sensing
  • LANDSAT Uses: Studies agriculture, forests, oceans, geology, hydrology and land use.
  • Radar Satellites: Can work day and night and through clouds, mist and fog.
  • India’s Contribution: National Remote Sensing Agency (NRSA), Hyderabad, established in 1972, plays an important role in remote sensing.
CISCE: Class 12

Key Points: Application of Remote Sensing in Geography

  • Importance in Geography: Remote sensing provides quick, accurate and reliable data for studying physical and human features.
  • Agriculture & Land Use: Used for crop estimation, yield prediction, land use mapping and drought monitoring.
  • Water Resources: Helps in flood mapping, groundwater potential mapping and identifying erosion-prone areas.
  • Ocean & Coastal Studies: Used for monitoring coastal environment and studying marine resources.
  • Forestry & Environment: Helps in forest mapping, forest density study and assessing environmental impacts.
CISCE: Class 12

Key Points: Geology and Mineral Resources

  • Geology & Mineral Resources: Remote sensing helps in studying faults, fractures and locating mineral resources (Project Vasundhara).
  • Forest Mapping: Used to estimate forest cover and identify dense, open and mangrove forests.
  • Wasteland Mapping: Helps in identifying and classifying wasteland areas across India.
  • Water & Soil Mapping: Used for groundwater potential maps and nationwide soil resource mapping.
  • Drought Monitoring: Helps in early warning and management of drought conditions.
  • Urban & Landuse Studies: Used to study urban sprawl and land use changes in major cities.
  • Snow & Marine Studies: Helps in estimating snow melt runoff and identifying marine fishery potential zones.
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