What occurs when light passes from air into glass?

When light passes from air into glass, it slows down due to the higher refractive index of glass compared to air. The behavior of light as it enters a new medium is governed by Snell's Law, which states that the ratio of the sine of the angle of incidence to the sine of the angle of refraction is equivalent to the ratio of the velocities of light in the two media.

As light moves into a denser medium like glass, its speed decreases. This change in speed causes the light to bend towards the normal line, which is an imaginary line perpendicular to the boundary surface between the two media. Because the refractive index of glass is greater than that of air, the light ray will refract toward the normal rather than away from it.

Understanding this phenomenon is crucial in optics, as it illustrates fundamental principles about how light interacts with different materials.