Question

Give the shape of interference rings observed in a Young's double slit experiment.

Answer 1

actually, Fringes are neither Image nor shadow of silt but locus of a point which moves such a way that Its path difference from the two sources remains constant.

but we know, from mathematics,
The difference of the focal distances of any point on the hyperbola is constant.

so, In Young's double slits experiment(e.g., YDSE) , the Interference fringes for two coherent point sources are hyperboloid.

but it's not true that shape of interference rings observed in Young's double slit experiment is only in hyperboloid , it also maybe circular, linear, elliptical etc... just depends on depending on the orientation of the screen with respect to slits .

Answer 2

Answer:

interference fringes of different shapes (a) generates circular fringes when the observation point lies on a line perpendicular to the line joining the two sources of light, i.e., when two mirrors are parallel to each other and (b) generates straight or conic fringes when the mirrors are inclined at an angle