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Sunday, September 20, 2015

WHAT IS ELECTROMAGNETIC WAVE?


Electricity and magnetism are different facets of electromagnetism. This connection first elucidated by Faraday, Maxwell.

 
Faraday’s Law:  A changing magnetic field will create an electric field.  The direction of the electric field will be perpendicular to the direction of the magnetic field.

Maxwell’s Proposal:  A changing electric field will create a magnetic field.  The direction of the magnetic field will be perpendicular to the direction of the electric field.




RELATION BETWEEN ELECTRICITY & MAGNETISM

A changing magnetic field produces an electric field, and a changing electric field produces a magnetic field.

Electric and Magnetic fields can produce forces on charges

An accelerating charge produces electromagnetic waves (radiation)

Both electric and magnetic fields can transport energy
      Electric field energy used in electrical circuits, e.g., released in lightning
      Magnetic field carries energy through transformer

ELECTROMAGNETIC WAVE

The electromagnetic wave is looked at as sinusoidal waves which are composed of a combination of two fields which are i) electric field and ii) a magnetic field at right angle to that electric field.




 

All electromagnetic radiation travels at c =  3x108 m/s in vacuum – real number is 299792458.0 m/s exactly

Examples of Electromagnetic Radiation

          AM and FM radio waves (including TV signals)
          Cell phone communication links
          Microwaves
          Infrared radiation
          Light
          X-rays
          Gamma rays
 

Uses of Electromagnetic Waves
 
•  Communication systems
    Radar
    Cooking (with microwaves)
    Medical Imaging (X rays)
    “Night Vision” (infrared)
     Astronomy (radio, mwave, IR, visible, UV, gamma)