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When the angle of incidence exceeds a certain limiting angle, known as the critical angle, total internal reflection occurs. The two prerequisites for total internal reflection are as follows:
- The angle of incidence in the denser medium must be greater than the critical angle for that pair of media.
- Before reaching a rarer medium, a ray of light must pass through a denser medium.
The laws of reflection state that when a light ray passes through an optically denser medium and strikes an optically rarer medium at an angle greater than the critical angle for both media, the ray is reflected in the medium. In 1611, Johan Kepler, a German astronomer and mathematician, discovered the wonder of total internal reflection. Total inner reflection is important in fibre optics and is used in polarising crystals. Telescopes, microscopes, binoculars, spectroscopes, periscopes, and other optical instruments use the total internal reflection of light.
When a ray of light travels from water to air, the light gets refracted at the point where the air and water meet. When light passes from a medium with a high refractive index (water) to one with a low refractive index (air), the light bends away from the normal.
The incident ray of light is refracted in such a way that it passes at a specific angle of incidence, called the critical angle, along the water’s surface. In this case, the refraction angle is 90 degrees. The incident ray is reflected back to the medium when the angle of incidence is greater than the critical angle, causing the phenomenon known as total internal reflection.
Total Internal Reflection within The Prism
Right-angled crystals are used in many optical instruments, including cameras, binoculars, periscopes, and telescopes, to reflect a light bar through 90° or 180° (total inside reflection). One of the right-angled prism’s points is 90°. Two of these crystals are used in the periscope. The crystal reflects the sunlight at an angle of 180°. Two of these crystals are used in binoculars.
Endoscopy
The property of total internal reflection in sunlight allows for the use of an endoscope.
Endoscopes use optical fibres to create a picture of the inside of the body. A doctor can insert a bundle of fibres into the body. Only a few fibres carry light into the body, while the rest reflect light back out from the body’s internal surfaces. Endoscopes are used to detect and measure total internal reflections, which occur when a propagating wave strikes a medium boundary at an angle greater than a critical angle.
Optical Filaments
High-quality quartz fibres or composite glass are used to make these. Each fibre has a core and cladding. The cladding has a higher ratio than the middle material. The cladding is a rarer medium, whereas the contrast within the centre’s refractive record is a denser medium. Because light experiences total internal reflection at each arrangement, when proof in the form of sunshine is coordinated at one end of the fibre at an affordable point, there is no calculable misfortune within the sunshine. Using a prism, you can change the size of images without changing their shape.
Conclusion
Total internal reflection is important in fibre optics, and it is used in polarising prisms. Total internal reflection is the reflection of light that strikes a medium boundary at a point other than the fundamental point relative to the surface.
When a pencil is placed in a glass of water, the light rays bending far from their normal path and appearing closer to the surface from parts of the pencil submerged in water give the impression that the pencil is broken. Total inner reflection is important in fibre optics and is used in polarising crystals. Telescopes, microscopes, binoculars, spectroscopes, periscopes, and other optical instruments use the total internal reflection of light. Medium 1 should have a higher refractive index than medium 2 because light must travel from an optically denser medium to an optically rarer medium. In an optically denser medium, light travels slower than in an optically rarer medium. The angle of incidence must be greater than the critical angle.
