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Question 2: What is the difference between interference and diffraction?


Major difference between interference and diffraction is that in the case of interference, two waves superpose with one another. At some points they reinforce one another and at other they cancel the effect of one another. Where they reinforce one another,the resultant amplitude is larger and we see high intensity of light at the point. Where they cancel one another the resultant amplitude is either zero or quite weaker. We see lower intensity of light at those points. Whereas in the case of diffraction, light waves spread toward the edges of a narrow opening or an obstacle in its path.

Other differences are summarized asfollow;

Interference Diffraction
Interference occurs between two coherent waves on the minimum. For diffraction to take place, a single opening or sharp edge will suffice.
Bright bands have uniform intensity in interference pattern. In case of diffraction, the bright bands gradually decrease.
In interference, the fringes are equally spaced. The width of fringes decreases in the case of diffraction.


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