A thin sheet of glass `(mu=1.520)` is introduced normally in the path of one of the two interfering waves. The central bright fringe is observed to shift to position originally occupied by the fifth bright fringe. If `lambda=5890Å`. Find the thickness of the glass sheet.

Explanation

`Delta x = (mu - 1)t = n lamda` . It is given that `mu = 1.60, n = 12,lamda = 5890 Å`
` therefore t = (12 xx 5890 xx 10^(-10))/(1.60 - 1)`
` = 1.18 xx 10^(-5) m = 12mu m`