1. When a beam of light is incident on a glass slab at an angle, refraction and lateral deviation occurs. Refraction is the change in direction of the light beam when it passes from one medium to another of different optical density.
2. The refracted ray travels along a straight line inside the denser medium and emerges out when it reaches the second surface. The emergent ray is the ray that passes out of the denser medium.
3. The angle of incidence and refraction are related by Snell's law of refraction, where the ratio of sines of the angles is equal to the ratio of velocities of light in the two media. The perpendicular distance between the incident and emergent