Class 12 Physics Wave Optics Coherent Incoherent sources

Coherent & Incoherent sources

  • Coherent sources are those sources of light which emit waves that have same frequency and zero or constant phase difference.
  • Suppose if there are 2 sources S1 and S2 are coherent sources if there frequencies are same and also phase difference between them is either 0 or constant.
  • Phase difference should not change.


  • For example:-Laser light.
  • Incoherent sources are those which sources of light which emit waves that have random frequencies and phase differences.
    • There is no relationship between the waves in terms of frequencies and phase difference.
    • For example:-Electric bulb, night lamp.


Coherent Source


Incoherent Sources


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