The n transparent slabs of refractive index1.5 each having thickness 1cm, 2 cm,…to n cm are arranged one over another. A point object is seen through this combineation with near perpendicular light. If the shift of object by the combination is 1 cm, then find the value of n.

Explanation

`x= `total shift
`x=x_(1)+x_(2)+…+x_(n)`
`=t_(1)(1-(1)/(mu))+t_(2)(1-(1)/(mu))+...+t_(n)(1-(1)/(mu))`
or `1cm =(1-(2)/(3))1+2+3+…+n`
`1=(n(n+1))/(6)`
`6=n(n+1)rArrn=2`