Two immiscible liquids of refractive indices 8/5 and 3/2 respectively are put in a beaker as shown in the figure. The height of each column is 6 cm.…

Two immiscible liquids of refractive indices $\displaystyle \frac{8}{5}$ and $\displaystyle \frac{3}{2}$ respectively are put in a beaker as shown in the figure. The height of each column is $\displaystyle 6$ cm . A coin is placed at the bottom of the beaker. For near normal vision, the apparent depth of the coin is $\displaystyle \frac{\alpha}{4} \mathrm{~cm}$. The value of $\displaystyle \alpha$ is $\displaystyle \_\_\_\_$.