A cube of edge 6 cm is placed over a printed page. At what distance from the top surface of cube will the letters appear when seen from above? Refractive index of glass is 1.5

Dear Student,

This is the concept of Real depth and apparent depth.

The formula for the same is given by, $\mathrm{\mu }=\frac{\mathrm{Real} \mathrm{depth}}{\mathrm{Apparent} \mathrm{depth}}$
Here, the letters printed on the printed page is at 6 cm, which signifies the real depth of the letters. 

Refractive index is given - 1.5, we get

$$\begin{gathered} 1.5=\frac{6}{\mathrm{Apparent} \mathrm{depth}} \\ \Rightarrow \mathrm{Apparent} \mathrm{depth}=\frac{6}{1.5} \\ \Rightarrow \mathrm{Apparent} \mathrm{depth}=4 \mathrm{cm} \end{gathered}$$

 At 4 cm from the top surface of cube will the letters appear when seen from above of the cube.