What is the interference? let us check out the details……

     When two light waves super impose , then the resultant amplitude (or) intensity in the region of superposition is different than the amplitude of individual waves. This modification in the dstribution of intensity inthe region of super position is called “INTERFERENCE”.


               The redistribution of energy due to superposition of waves from coherent sources, reslulting in bright and dark bands (or) frings is called interference.

Now lets check out the types of interference. The interference is of two types. They are:


Constructive interference:

                        When two resultant amplitude is the sum of the amplitudes due to two waves, this interference is kinown as cunstructive interference.
let ‘a’ be the amplitude of each wave then the resltant dispalcement is given by 

                            y = a + a ==> y = 2a ( for two waves).  


                           When the resultant amplitude is equal to the difference of the two amplitudes, tis interference is known as destructive interference.
let ‘a’ be the amplitude of each wave then the resultant displacement is given by 

y = a – a ==> y = 0


  1. The two light sources emitting light waves should be coherent.
  2. The two sources must emit countinous light waves of same wave length and frequency.
  3. The separation between two sources and teh screen should br large.
  4. The distance two sources and the screen ahold be large. 
  5. To view interference frings, the sources should be monocromatic.

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