In a Fresnel's biprism setup, monochromatic light of wavelength 550 nm is used to obtain interference fringes on the screen. On introducing a thin sheet of transparent material of thickness 1.1 microns in the path of one of the interfering beams, the central fringe is shifted through distance equal to the spacing between successive bright fringes. Then, the refractive index of the transparent material is

In a Fresnel's biprism setup, monochromatic light of wavelength 550 nm

1.	In a Fresnel's biprism setup, monochromatic light of wavelength 550 nm is used to obtain interference fringes on the screen. On introducing a thin sheet of transparent material of thickness 1.1 microns in the path of one of the interfering beams, the central fringe is shifted through distance equal to the spacing between successive bright fringes. Then, the refractive index of the transparent material is
A.	1.7
B.	1.5
C.	1.4
D.	1.6
Answer» C. 1.4