Question

why in Newton rings the centre spot is always dark
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Answer 1

The central fringe in Newton's rings is dark in the case of the reflected system because the air film thickness formed at the centre between the glass plate and the lens is zero. Hence, at the geometrical path difference between the incident and reflected rays from the glass plate is zero.

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Answer 2

Answer:

$\huge\it\blue{Answer :-}$

The central fringe in Newton's rings is dark in the case of the reflected system because the air film thickness formed at the centre between the glass plate and the lens is zero. Hence, at the geometrical path difference between the incident and reflected rays from the glass plate is zero.

Explanation:

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