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.

.