When light passes from a less dense to a more dense medium, what occurs?

When light travels from a less dense medium, such as air, into a more dense medium, like water or glass, it experiences refraction. This process causes the light rays to change direction as they enter the new medium. The key principle at play here is that light travels slower in more dense materials compared to less dense ones.

As the light enters the more dense medium, the change in speed results in the light bending towards the normal line, which is an imaginary line that is perpendicular to the surface at the point of incidence. This bending occurs due to the difference in optical density between the two materials; light rays always seek the path that minimizes travel time, which results in this curvature towards the normal when entering a denser medium.

This phenomenon is crucial in many applications, such as lenses and optical instruments. Understanding how light behaves in different media is fundamental to grasping the principles of optics.