Refraction Through A Prism

The apparent depth of an object in a medium is given by the formula: where is the refractive index of the medium. For the bubble in water, the real depth is the sum of the depth of the bubble (8 cm) and the distance from the surface to the bubble (24 cm), giving a total real depth of 24 cm.
Since the refractive index of water is , the apparent depth of the image in the plane mirror will be:
Thus, the apparent depth of the image is 24 cm.

When a light wave passes from one medium to another, the phase change occurs due to the difference in the refractive indices of the two media. However, if the refractive index of the second medium is twice that of the first, there is no phase change due to the symmetry in the refractive index. In this case, the refractive indices of the first and second media are and respectively.
Since no significant phase reversal occurs when transitioning between media with such refractive index ratios, the phase change is .