Question

A thin sheet of glass (refractive index 1.5) of thickness 6 microns, introduced in the path of one of the interfering beams in a double-slit experiment shift the central fringe to a position earlier occupied by the fifth bright fringe. The wavelength of light used is
A. `3000Å`
B. `6000Å`
C. `4500Å`
D. `7000Å`

Answer 1

Correct Answer - B
`y_(0)=(mu-1)tD/d=5(Dlambda)/d`
`lambda=((mu-1)t)/5=((1.5-1)xx6xx10^(-6))/5`
`=6xx10^(-7)m=6000 Å`