Why does light suffer refraction and get deviated away from normal when it passes from water to air?

When a ray of light passes from one medium to another, its direction (except for ) changes because of change in its speed. A light ray suffers reflection and refraction at the boundary in passing from air to water. Air is a rarer medium while water is denser than air with refractive index of 1.33.

Why ray of light incident normal normally on the surface traverses its path back?

The reason for light falling on the centre of curvature gets reflected back along the same path is due to the angle of incidence and the angle of reflection lie along the normal for a concave mirror. Hence, the angle of reflection tends to zero degree, thus the ray of light retraces its path.

What is the lateral displacement when a ray of light falls normally on a glass slab?

When the ray of light falls normal to the glass slab then the emergent ray will be same as incident ray i.e. normal to the glass slab. So, the lateral displacement will be zero because of no deviation.

When a ray undergoes refraction through a plane glass slab the deviation at first surface is?

On passing through a glass slab, a ray of light suffers two refractions. Net deviation of the ray in the two refraction is zero.

What happens when a light ray travels along the normal?

When light rays travel from air into glass or from air into water, it bends towards normal. Case 2: When light rays travel from optically denser medium to rarer medium then they bend away from the normal. In this case the angle of refraction is greater than angle of incidence.

When a ray of light is incident normal to the surface?

Angle of reflection = infinity.

When a ray of light falls normally on the surface separating the two media it passes?

1. Incident ray is reflected back along the same path. 2. Angle if incidence is zero and angle of reflection will be zero [according to laws of reflection] .

What is lateral displacement of light ray?

When a light ray passes through a glass slab it is refracted twice at the two parallel faces and finally emerges parallel to its incident direction. Suppose a light ray enters the glass slab from air. It will first be refracted at this surface. The distance between these two rays is called the lateral displacement.