Rehana Jamal

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Dated 29/10/14
Lecture 2 P1
Database Management System Applications of
Remote sensing and GIS
Subject
Topics
Characteristics of Electromagnetic
radiation Wavelength regions of
electro-magnetic radiation
Presented by Rehana Jamal
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Characteristics of Electromagnetic radiation
Electromagnetic Energy can be modelled in two
ways i. By waves ii. By Photons(Energy bearing
particles)
Electromagnetic waves consist of a combination of
oscillating electrical and magnetic fields,
perpendicular to each other.
Distance
Velocity of light, c
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Characteristics of Electromagnetic radiation

• It can travel through empty space.
• The speed of light is constant in space.
• A wavelength Distance between crests or troughs
  through visible light
• Velocity 186,000 miles per second or300,000
  kilometers per second or 299,790,000m/s or 3108
  m/s
• Amplitude The amplitude of electromagnetic waves
  relates to its intensity or brightness(as in the
  case of visible light)
• Frequency
• The number of crests of the waves that pass by a
  point per second.
• Measured in units of hertz(Hz)
• 1 hertz 1 wave crest/second

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/ Crest
Velocity of light, c
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Thus, there is an inverse relationship between
wavelength and frequency
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Relation between the speed of light (c),
wavelength ( ), and frequency (f or V )
Thus (frequency f/V wavelengthlambda) is
equal to a constant (c)
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Sources of electromagnetic radiation

• Sources of long wavelengths
• Sources of visible light
• Sources of short wavelength
• Detectors of electromagnetic radiation

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Note the trends bluer light has shorter
wavelength, higher frequency, and more energy.
Redder light has longer wavelength, lower
frequency, and less energy.
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The unit of length chosen to describe a
particular wavelength is typically dependent on
the type of electromagnetic radiation
Unit Symbol Length (m) Type of Radiation
Angstrom Å 10-10 X-ray
Nanometer nm 10-9 UV, visible
Micrometer µm 10-6 Infrared
Millimeter mm 10-3 Infrared
Centimeter cm 10-2 Microwave
Meter m 1 TV, radio
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Types of Energy Resources

• In respect to the type of Energy Resources
• Passive Remote Sensing Makes use of sensors that
  detect the reflected or emitted electro-magnetic
  radiation from natural sources.
• Active remote Sensing Makes use of sensors that
  detect reflected responses from objects that are
  irradiated from artificially-generated energy
  sources, such as radar.
• In respect to Wavelength Regions
• Visible and Reflective Infrared Remote Sensing.
• Thermal Infrared Remote Sensing.
• Microwave Remote Sensing.

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In respect to the type of Energy Resources
Passive Remote Sensing
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In respect to the type of Energy Resources
Passive Remote Sensing
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In respect to the type of Energy Resources
Active Passive remote Sensing
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Wavelength regions of electro-magnetic radiation
Electro-Magnetic Spectrum (EMS)
Remote Sensing Technology makes use of the wide
range of Electro-Magnetic Spectrum (EMS) from a
very short wave "Gamma Ray" to a very long 'Radio
Wave'. Wavelength regions of electro-magnetic
radiation have different names ranging from Gamma
ray, X-ray, Ultraviolet (UV), Visible light,
Infrared (IR) to Radio Wave, in order from the
shorter wavelengths to the longer wavelengths.
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• Electromagnetic spectrum
• Definition The range of wavelengths for
  electromagnetic waves--from the very long to the
  very short--is called the Electromagnetic
  Spectrum. It includes following wavelengths
  bands
• Radio and TV waves are the longest usable waves,
  having a wavelength of 1 mile (1.5 kilometer) or
  more.
• Microwaves are used in telecommunication as well
  as for cooking food.
• Infrared waves are barely visible. They are the
  deep red rays you get from a heat lamp.
• Visible light waves are the radiation you can see
  with your eyes. Their wavelengths are in the
  range of 1/1000 centimeter.
• Ultraviolet rays are what give you sunburn and
  are used in "black lights" that make object glow.
  
• X-rays go through the body and are used for
  medical purposes.
• Gamma rays are dangerous rays coming from nuclear
  reactors and atomic bombs. They have the shortest
  wavelength in the electromagnetic spectrum of
  about 1/10,000,000 centimeter.

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Wavelength(mm)
Name
Optical wavelengthReflective portion (i)
Visible (ii) Near IR (iii) Middle IR Far IR
(Thermal, Emissive)
0.30-15.00.38-3.00 0.38-0.72 0.72-1.30 1.30-3
.00 7.00-15.0
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• In respect to Wavelength Regions
• Visible and Reflective Infrared Remote Sensing
• Thermal Infrared Remote Sensing
• Microwave Remote Sensing

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(1mm)
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Summary
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• References
• www.google.com
• www.wikipedia.com
• Principles of Remote sensing
• edited by Lucas L.E. Janssen

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• Possible Exam Questions
• Q1. Define the following
• Visible spectram
• Infrared wavelength region
• Optical wavelength range
• Radio wave band
• Q2.Differentiate the Passive remote sensing and
  Active remote sensing.
  5 Marks
• Q3.Define Electromagnetic spectrum. Describe in
  detail the all wavelength regions of
  electromagnetic spectrum. 15 Marks
• Q5.Write a not on EM spectrum. 5 Marks