Question

Give a demonstration for total internal reflection. What are the technological applications of total internal reflection in nature? Briefly explain it.

Answer 1

When light is incident upon a medium of lesser index of refraction, the ray is bent away from the normal, so the exit angle is greater than the incident angle. Such reflection is commonly called "internal reflection". The exit angle will then approach ${90}^0$ for some critical incident angle ${\theta }_c$ , and for incident angles greater than the critical angle there will be total internal reflection.
Total internal reflection is the operating principle of optical fibers, which are used in endoscopes and telecommunications. An optical fiber consists of a very thin core of high purity glass. The core is covered by a second layer (cladding) also made from high purity glass. The cladding is less dense than the core and has a lower refractive index for total internal reflection to occur. Thus light rays passing along the core at an angle greater than the critical angle are totally internally reflected. The surface of the high purity glass core acts like a perfect mirror and the light ray is continuously reflected along the length of the optical fiber core.