DHANALAKSHMI COLLEGE OF ENGINEERING
DEPARTMENT OF CIVIL ENGINEERING
CE6003 - REMOTE SENSING AND GIS
UNIT – 1 EMR & ITS INTERACTION WITH ATMOSPHERE AND EARTH MATERIAL
Part- A (2 marks)
1. What is Remote Sensing?
Remote sensing is the science and art of obtaining information about on object, area, or phenomena
through the analysis of data acquired by a device that is not in contact with the object, area, or
phenomena under investigation.
2. What is the application of Remote Sensing?
In many respects, remote sensing can be thought of as a reading process. Using various sensors, we
remotely collect data that M be analyzed to obtain information about the objects, areas, or phenomena
being investigated. The remotely collected data can be of many forms, including variations in force
distributions, acoustic wave distributions, or electromagnetic energy distributions.
3. Write the physics of Remote Sensing.
Visible light is only one of many forms of electromagnetic energy. Radio waves, heat, ultraviolet rays, and
X-rays are other familiar forms. All this energy is inherently similar and radiates in accordance with basic
wave theory. This theory describes electromagnetic energy as traveling in harmonic, sinusoidal fashion at
the “velocity of light” c. The distance from one wave peak to the next is the wave length ψ, and the number
of peaks passing a fixed point in space per unit time is the wave frequency V.
From basic physics, wave obey the general equation C = v y
4. What are the components of Remote Sensing?
a. The energy sources
c. Energy-matter interaction
d. The sensors
e. Data processing and supply system
f. Multiple data users.
5. What is Electro Magnetic Radiations?
Electromagnetic (EM) radiation is a self-propagating wave in space or through matter. EM radiation has an
electric and magnetic field component which oscillate in phase perpendicular to each other and to the
direction of energy propagation.
6. What is the significance of EMR in remote sensing?
EMR stands for electromagnetic radiations. It is the energy emitted reflected from ground features and
transmitted to the sensing instrument in the form of waves. This emitted energy/radiant energy is called
electromagnetic radiation. The remote sensing of land surface features is based on detection of
electromagnetic radiation. The water vapour. Oxygen, ozone, Co2 etc present in the atmosphere
influence EM radiation through the mechanism of 1. Scattering 2. Absorption.
7. What are the types of Electromagnetic radiation?
Electromagnetic radiation is classified into types according to the frequency of the wave, these types
include (in order of increasing frequency): radio waves, microwaves, terahertz radiation, infrared radiation,
visible light, ultraviolet radiation, X-rays and gamma rays.
8. Draw the quantum theory interaction.
A quantum theory of the interaction between electromagnetic radiation and matter such as electrons is
described by the theory of quantum electrodynamics.
9. Explain refraction.
In refraction, a wave crossing from one medium to another of different density alters its speed and
direction upon entering the new medium. The ratio of the refractive indices of the media determines the
degree of refraction, and is summarized by Snell's law. Light disperses into a visible spectrum as light is
shone through a prism because of refraction.
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