Optics 6 Question 25
27. 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
(a) straight
$(1999,2 M)$
(b) circular
(c) equally spaced
(d) having fringe spacing which increases as we go outwards
Show Answer
Solution:
- 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.
