Explanation of Emergent Ray being Parallel to Incident Ray

When a light ray passes from one medium to another, it undergoes a change in its direction. This change in direction of the light ray is known as refraction. The angle of refraction depends on the angle of incidence and the refractive indices of the two media. In some cases, the emergent ray is parallel to the incident ray. This phenomenon occurs under certain conditions, which we will discuss in detail below.

Explanation of Refraction

Refraction is the bending of a light ray when it passes from one medium to another. The amount of bending depends on the angle of incidence and the refractive indices of the two media. When a light ray passes from a less dense medium to a more dense medium, it bends towards the normal. On the other hand, when a light ray passes from a more dense medium to a less dense medium, it bends away from the normal.

Conditions for Emergent Ray being Parallel to Incident Ray

When a light ray passes from a more dense medium to a less dense medium, the angle of refraction can be such that the emergent ray is parallel to the incident ray. This occurs when the angle of incidence is greater than the critical angle.

The critical angle is defined as the angle of incidence at which the angle of refraction is 90 degrees. When the angle of incidence is greater than the critical angle, the light ray undergoes total internal reflection. This means that all of the light is reflected back into the more dense medium. When the angle of incidence is equal to the critical angle, the emergent ray is parallel to the interface between the two media.

Examples of Emergent Ray being Parallel to Incident Ray

One common example of this phenomenon is the mirage. In a hot desert, the air near the ground is hotter and less dense than the air above it. When light passes from the hotter, less dense air to the cooler, denser air above it, it bends away from the normal. This causes the image of the sky to be reflected towards the ground, creating the illusion of water on the road.

Another example is the optical fiber. Optical fibers are made of glass or plastic and are used to transmit light over long distances. The refractive index of the core of the fiber is greater than that of the cladding. This means that when light enters the fiber at an angle greater than the critical angle, it undergoes total internal reflection and travels down the fiber without losing energy. The light emerges from the end of the fiber parallel to the incident ray.

Conclusion

In summary, the emergent ray can be parallel to the incident ray when the angle of incidence is greater than the critical angle. This occurs due to total internal reflection, which causes all of the light to be reflected back into the more dense medium. This phenomenon is important in many applications, such as optical fibers and mirages.

Yes , Emergent ray is parallel to incident ray when it's passed from an object having both side parallel (e.g glass slab). but they are not parallel when the two faces , from where light have to come or go are not parallel. (ex. Glass prism) . (It will more clear. when you relate refraction of light ch. and eye ch. of physics).