Constructive and destructive interferenceof light waves is also the reason why thin films, such as soap bubbles, show colorful patterns. This is known as thin-film interference, because it is the interferenceof light waves reflecting off the top surface of a film with the waves reflecting from the bottom surface
2 sources must be coherent i.e phase difference is zero or constant.So that lights will travel in same direction .Due to this a distinct interference of light is obtained . hope this helps U...
These are related but not exactly the same. ``Interference'' is the more general concept: it refers to the phenemenon of waves interacting. Waves will add constructively or destructively according to their phase difference. ``Diffraction'' usually refers to the spreading wave pattern from a finite-width aperture.
Let are intensities of two waves. When two waves superimpose on each other, interference pattern is formed.
The maximum intensity is given by :
The minimum intensity is given by :
Dividing equation (1) and (2) we get :
So, the ratio of maximum and minimum intensity should be 9:4.
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Topic : Interference
The diagram shown below illustrates the
possible paths followed by a light ray as it enters a
lens (n = 1.56) covered with a
Destructive interference occurs when the maxima of two waves are 180 degrees out of phase: a positive displacement of one wave is cancelled exactly by a negative displacement of the other wave. The amplitude of the resulting wave is zero. The dark regions occur whenever the waves destructively interfere.
This phenomenon can occur because the medium is moving in the opposite direction to the wave, or it can arise in a stationary medium as a result of interference between two waves traveling in opposite directions.