Glass Slab Emergent Ray Direction Explained
When a ray of light passes through a rectangular glass slab, it undergoes refraction twice: once upon entering the slab and again upon exiting.
First Refraction: Light enters the glass slab from air. Since glass is optically denser than air, the light ray bends towards the normal.
Second Refraction: The light ray exits the slab from the parallel face back into the air. As it moves from a denser medium (glass) to a rarer medium (air), the light ray bends away from the normal.
Crucially, because the entry and exit faces of the rectangular slab are parallel, the angle of incidence at the first surface equals the angle of emergence at the second surface relative to the normal. This geometry ensures that the emergent ray is parallel to the original incident ray. The ray experiences a lateral displacement but maintains its original direction.
Therefore, the emergent ray is parallel to the incident ray.
Important Questions from Refraction and Reflection
Which of the following is NOT an example of refraction of light?
If the object distance and the image distance from a concave mirror is -20 cm, what is the focal length of the mirror?
Water drops shine on a lotus leaf due to:
A convex lens 'A' of focal length $10 \text{ cm}$ and another convex lens 'B' of focal length $20 \text{ cm}$ are kept along the same axis with a distance '$d$' between them. If a parallel beam of light falling on 'A' leaves 'B' as a parallel beam, then the distance '$d$' in $cm$ will be :
- A ray is incident at an angle of incidence $i$ on one surface of a small angle prism (with angle of prism $A$ and refractive index $\mu$). The ray emerges normally from the opposite surface, causing a total angle of deviation $\delta$ from its original path. Assuming all angles are small, the angle of incidence $i$ is nearly equal to:
