JNTU B.Tech IV REMOTE SENSING AND GIS IN MINING Previous Question Paper (July/August - 2022 - R18)

Electromagnetic Radiation (EMR) is a form of energy that propagates through space as synchronized oscillations of electric and magnetic fields. It travels at the speed of light and does not require a medium for propagation. The salient features of EMR include:

• Wave Nature: EMR is characterized by wavelength (λ), frequency (ν), and amplitude. The relationship is defined by the formula:
  c = νλ
  where c is the speed of light (approximately 3x10⁸ m/s).
• Electromagnetic Spectrum: EMR spans a continuous range of energies, from high-energy gamma rays and X-rays to ultraviolet, visible light, infrared, and low-energy microwaves and radio waves.
• Particle Nature: EMR also behaves as discrete packets of energy called photons, where energy (E) is proportional to frequency:
  E = hν
  (h is Planck's constant).
• Interaction with Matter: When EMR strikes a surface, it can be absorbed, transmitted, or reflected. The specific spectral signature of an object depends on how it interacts with different wavelengths of EMR.

In Remote Sensing, EMR acts as the information carrier between the target and the sensor. The process involves:

1. Energy Source: Remote sensing utilizes either passive systems (detecting reflected solar radiation or emitted thermal radiation) or active systems (transmitting its own EMR pulses, like Radar or LiDAR).
2. Atmospheric Interaction: As EMR travels through the atmosphere, it undergoes scattering and absorption. Sensors are designed to operate within specific 'atmospheric windows' where the atmosphere is transparent.
3. Target Interaction: The sensor measures the EMR reflected or emitted by the Earth's surface. Different materials (e.g., minerals, vegetation, water) exhibit unique spectral reflectance curves, allowing for identification and classification.
4. Detection and Recording: Sensors convert the incoming EMR into electrical signals, which are digitized and processed to create imagery, enabling the analysis of mining areas, geological features, and environmental changes.