Question

A glass slab of thickness 18 cm and refractive index $\frac{3}{2}$ is placed on a printed matter. The normal shift of the printed matter is

• A. 3 cm
• B. 6 cm
• C. 9 cm
• D. 12 cm

Answer 1

Answer: (B)

6 cm

We know that, Refractive index is $\mu =\frac{\text{Real Depth}}{\text{Apparent Depth}}$

Given the Real depth $d_{\text{real}}=18\text{cm}$

Refractive index $\mu =1.5$

Thus, Apparent depth $d_{\text{apparent}}=\frac{d_{\text{real}}}{\mu }=\frac{18}{1.5}=12\text{cm}$

Thus Normal Shift = Real Depth - Apparent Depth$=18-12=6\text{cm}$