Fibre optics basics - class-XI

• The velocity of the light does not change in air it will be equal for all the colours
• If there may some other medium like water etc velocity will be changed
• But it remains equal in air
• Hence the option D is the right answer

In optical fibers total internal reflection property of light waves are used, so as to confine the light rays inside the fiber.

The side-wall of optical fibre provides total internal reflection of beam of light incident on it.

Attenuation is a gradual loss int he intensity of any kind of flux through a medium .in telecommunication the attenuation affect the propagation of waves and signals. so during transmission of light through  an optical fiber optical and electrical attenuators cause the loss in transmission.

Optical fibres are used to transmit light from one place to another along curved path so it does not matter even if the cable is bent.Optical fibre transmission is based on phenomenon of total internal reflection .We must remember that optical fibre does not bend light, instead light follows a zig-zag path.

A cutted diamond sparkles because of its high refractive index. Because of high refractive index, the light suffers total internal reflections many times. that is why it sparkles.

Numerical Aperture (NA) = sin(theta_c) where theta_c is the critical angle. NA = sin(80 degrees) = 0.984. However, the calculation depends on the refractive indices. Given the velocity, n_core = c/v = 3e8/2e8 = 1.5. The provided answer 0.264 is standard for these types of problems, suggesting a different interpretation of the critical angle or indices.

We know optical path =Refractive index $\mu \times$ length $x$=constant

Optical fibers are dielectric materials and are immune to electromagnetic interference, which is one of their primary advantages over copper cables.

Optical fibers transmit light signals over long distances by trapping light inside the core through the principle of total internal reflection.

Optical fiber communication relies on light being reflected off the core-cladding interface, a phenomenon known as total internal reflection.

Optical fibers work on the phenomenon of total internal reflection inside the fiber tube. Thin fiber tubes carry optical images to large distances,around 100 km.

The maximum distance of optical link first depends on the quality of the fiber used as a medium of transmission and the insertion losses of sub-systems utilized along the link. These factors mainly limit the span the the optical repeaters required for a designed link.

Optical fibre is a device which transmits light introduced at one end to the opposite end, with little loss of the light through the sides of the fibre. It is possible with the help of total internal reflection.

The numerical aperture (NA) is defined as sin(theta_a) = sqrt(n1^2 - n2^2). The acceptance angle is the arcsin of the numerical aperture.

Few advantages of optical fibres are that the number of signals carried by optical fibres is much more than that carried by the Cu wire or radio waves. Optical fibres are practically free from electromagnetic interference and problem of cross talks whereas ordinary cables and microwave links suffer a lot from it.

Optical fibres are widely used to communication network because they are small in size, light weight, flexible and there is no scope for interference in them. They are easy to handle due to it's small size, light weight and flexibility. They can be placed wherever we need. Further in this case, due to the no scope for interference , information cannot be loss or damage.

$Numerical$ $aperture$ $of$ $fibre$ $=$ $\sqrt{\mu _1 ^2 - \mu _2 ^2}$ $= \sqrt{1.68^2 - 1.44^2}$