As light moves from air into water or glass, it moves the normal.As light moves from water or glass into air, it moves the normal.

When light travels from one medium to another, such as from air to water or glass, it changes speed, which causes it to refract or bend.

1. Light moving from air to water or glass: In this case, light enters a denser medium (water or glass) from a less dense medium (air). During this transition, the light ray bends towards the normal line (an imaginary line perpendicular to the surface at the point of incidence). This bending occurs because light travels slower in denser media, leading to a decrease in speed and direction change.

2. Light moving from water or glass to air: Conversely, when light exits a denser medium into a less dense medium, it bends away from the normal. This happens as the light transitions back into air, where it can travel faster. The properties of refraction can be quantitatively described by Snell's Law, which relates the angles of incidence and refraction to the refractive indices of the two media.

In summary, light moves towards the normal when entering a denser medium and away from the normal when entering a less dense medium. This phenomenon is essential for understanding various optical applications, including lenses and vision correction.