Question

What is the nature of central fringe in Newtons rings experiment

Answer 1

Nature of central fringe in Newton's ring experiment:

The central fringe in the newton ring experiment is dark. It is because at the center the thickness of the air film made between lens and glass plate is 0. So, at the central fringe the geometrical path difference between the incident rays and reflected rays from glass plate is 0, but due to reflection a path difference of is familiarized. This path difference gives critical interference at the center and therefore center is dark.

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