On introducing a thin mica sheet of thickness  1×10−6m   and refractive index  1.5  in the path of the waves, central bright maxima shifts by  'n' fringes.  Wavelength of wave used is 5000 A0 , then  'n'  is

Thickness of mica sheet t=1×10−6 m Refractive index μ=1.5 Wavelength λ=5000 A0=5000×10−10 m Number of fringes n=?          n=(μ−1)tλ             =(1.5−1)1×10−65000×10−10              =0.5×10−65×10−7         ∴n=1