Optics Ques 141
- A thin slice is cut out of a glass cylinder along a plane parallel to its axis. The slice is placed on a flat plate as shown. The observed interference fringes from this combination shall be
$(1999,2 M)$
(a) straight
(b) circular
(c) equally spaced
(d) having fringe spacing which increases as we go outwards
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Answer:
Correct Answer: 141.(a)
Solution:
Formula:
- Locus of equal path difference are the lines running parallel to the axis of the cylinder. Hence, straight fringes are obtained.
NOTE: Circular rings (also called Newton’s rings) are observed in interference pattern when a plano-convex lens of large focal length is placed with its convex surface in contact with a plane glass plate because locus of equal path difference in this case is a circle.
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