Question
Sat November 26, 2011 By:

what is the difference between interference and diffraction

Expert Reply
Sun November 27, 2011
1. Interference is due to superposition of two distinct waves coming from two coherent sources. Diffraction is a result of superposition of the secondary wavelets coming from different parts of the same wavefront.
2. In interference, all bright bands are of same intensity; while in diffraction pattern, all bright bands are not of same intensity.
3. In interference pattern, intensity of minima is generally zero or very small and there is a good contrast between bright and dark fringes. In diffraction pattern, intensity at minima is never zero and there is a poor contrast between bright and dark bands.
4. The width of interference fringes may or may not be equal; but the width of diffraction bands is always unequal.
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