Question

A flat glass slab of thickness 6 cm and refractive index 1.5 is placed in front of a plane mirror. An observer is standing behind the glass slab and looking at the mirror. The actual distance of the observer from the mirror is 40 cm. The distance of his image from himself as seen by the observer is

• A. 74 cm
• B. 76 cm
• C. 78 cm
• D. 80 cm

Answer 1

The correct option is B 76 cm

$\begin{array}{c}\text{D(apparent) of mirror from O:}\\ =1\times (\frac{34}{1}+\frac{6}{1.5})\\ =34+4=38cm\\ \text{distance of image}=38\times 2=76cm\end{array}$