Young’s double–slit experiment is performed with light of wavelength λ=6000 A0 . A glass plate of thickness 0.01 mm  and μ=1.5  is introduced. The number of fringes shifting in the system is

Wavelength λ=6000 A0=6000×10−10 m Thickness t=0.01 mm=0.01×10−3 m Refractive index μ=1.5 Number of fringes shifted n=?      n=(μ−1)tλ         =(1.5−1)0.01×10−36000×10−10         =5×10−66×10−7         =8.33 ∴  Number of fringes shifted n=8