One face of a rectangular glass plate 6 cm thick is silvered. An object held 8 cm in front of the first face, forms an image 12 cm behind the silvered face. The refractive index of the glass is

Explanation

Apparent position of the silvered face is shifted towards the object by (8 - x)cm.

Hence 10 + x = 12 + (8 - x). [`because` object distance = image distance]
or, x = 5 cm.
Hence `mu=("Real thickness")/("Apparent thickness")=(8cm)/(5cm)=1.6`