Class 12 Physics Electromagnetic Waves Sources of Electromagnetic Waves

Sources of Electromagnetic Waves (EM)

  • EM waves are generated by electrically charged particle oscillates (accelerating charges).
  • The electric field associated with the accelerating charge vibrates which generates the vibrating magnetic field.
  • These both vibrating electric and magnetic fields give rise to EM waves.
  • If the charge is at rest,electric field associated with the charge will also be static.
    • There will be no generation of EM waves as electric field is not varying with time.
  • When the charge is moving with uniform velocity,thenthe acceleration is 0.
    • The change in electric field with time is also constant as a result again there will be no electromagnetic waves generated.
  • This shows that only the accelerated charges alone can generateEM waves.
  • For example:
    • Consider an oscillating charge particle,it will have oscillating electric field and which give rise to oscillating magnetic field.
    • This oscillating magnetic field in turn give rise to oscillating electric field and so on process continues.
    • The regeneration of electric and magnetic fields are same as propagation of the wave.
    • This wave is known as electromagnetic wave.
    • The frequency of EM waves= the frequency of the oscillating particle.

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