Consider a configuration of n identical units, each consisting of three layers. The first layer is a column of 3-1 1 air of height h = = cm, and the second and third layers are of equal thickness d = 2 3 refractive indices h = h unit, as shown in the figure. A ray of light from O is incident on the second layer of the first unit at an angle of 0=60 to the normal. For a specific value of n, the ray of light emerges from the bottom of the 8 configuration at a distance = cm, as shown in the figure. The value of n is_ 3 3 and = 3, respectively. A light source O is placed on the top of the first 2 0 I - cm, and Air 1 142 Air n units