Monichromatic lightof wavelenght 600 nm is used ina Young's double slilt experient. One of the slits is covered by a transparent sheet of thicknes `1.8xx10^-5` m made of a material of refractive index 1.6. How many fringe will shift due to the introduction of the sheet?

Explanation

As derived earlier, the total fringe shift `= (w)/(lambda) (mu - 1) t`
As each fringe width = w
The number of fringes that will shift is
`("Total fringe shift")/("Fringe width") = ((w)/(lambda) (mu - 1 )t) /(w)`
`=((mu - 1)t)/(lambda)`
`= ((1.6 - 1 ) xx 1.8 xx 10^(-5) m)/(600 xx 10^(-9)m) = 18`.