 For example, the RI of air is approximately 1.0003 and the RI of water is approximately 1.333.Snell's Law describes how electromagnetic waves change direction at the interface between two mediums with different IR; thus bubbles can be identified from the accompanying refraction and internal reflection even though both the immersed and immersing mediums are transparent.The above explanation only holds for bubbles of one medium submerged in another medium (e.g.