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Q. Write the conditions for stable interference pattern of light. For which colours the fringe width is minimum is Young's double slit experiment ?
Conditions for interference
(a) the two sources of light must be coherent in nature and have same frequency.
(b) the amplitudes of the interfering light waves must be same.
Since fringe width is inversely proportional to the wavelength of light and red light has maximum wavelength hence fringe width will be minimum for red light.