One face of a glass cube of side `0.06 m` from the face opposite to the silvered face. Object is 0.07 m away from the unsilvered face. Looking from the object side, the image of the object appears to be `0.11 m` behind the silvered face. Calculate the refractive index of material of glass.

Explanation

In Fig. `AB` is silvered face of the section of the cube shown. When seen from the side of `O`, let `AB` appear at `A'B'`.

Let `DA' = x`
Also `DA = 0.06 m`.
As image in plane mirror `A'B'` is as far behined the mirror as the object is in front, therefore
`0.07 + x = 0.11, x = 0.11 - 0.07 = 0.04 m`.
`mu = ("real depth")/("apparent depth") = (DA)/(DA') = (DA)/(x) = (0.06)/(0.04) = 1.5`