Tag: physics

Questions Related to physics

Optical fibres transmit light along its axis, by the process of :

physics option c: imaging fibre optics basics optical fibre the critical angle, total internal reflection and optical fibre

  1. total internal reflection

  2. refraction

  3. interference

  4. diffraction

Show answer
Correct Option: A
Explanation:

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

In an optical fibre during transmission of light

physics option c: imaging fibre optics basics optical fibre the critical angle, total internal reflection and optical fibre

  1. Energy increases.

  2. Energy decreases.

  3. No loss of propagation of energy takes place.

  4. Light partially reflects and refracts.

Show answer
Correct Option: C
Explanation:

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.

Which principle is the basis for the transmission of light through fiber optic cables even if the cable is bent?

physics option c: imaging fibre optics basics optical fibre the critical angle, total internal reflection and optical fibre

  1. Photoelectric effect

  2. Uncertainty principle

  3. Light diffraction

  4. Light polarization

  5. Total internal reflection

Show answer
Correct Option: E
Explanation:

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:

physics option c: imaging fibre optics basics optical fibre the critical angle, total internal reflection and optical fibre

  1. high refractive index

  2. hardness

  3. emission of light by the diamond

  4. absorption of light by the diamond

Show answer
Correct Option: A
Explanation:

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.

The velocity of light in the core of a step index fibre is $2\times { 10 }^{ 8 }m/s$ and the critical angle at the core-cladding interfere is ${ 80 }^{ 0 }$. Find the numerical aperture and the acceptance angle for the fibre in air. The velocity of light in vacuum is $3\times { 10 }^{ 8 }m/s$.

physics option c: imaging fibre optics basics optical fibre the critical angle, total internal reflection and optical fibre
  1. 0.264; $75.{ 3 }^{ 0 }$
  2. 0.464; $45.{ 3 }^{ 0 }$
  3. 0.364; $25.{ 3 }^{ 0 }$
  4. 0.264; $15.{ 3 }^{ 0 }$
Show answer
Correct Option: D

The optical path of a monochromatic light is the same if it goes through $2.00$ cm of glass or x cm of ruby. If the refractive index of glass is $1.510$ and that of ruby is $1.760$ find the value of x is _______ cm?

physics option c: imaging fibre optics basics optical fibre the critical angle, total internal reflection and optical fibre

  1. $1.716$

  2. $1.525$

  3. $2.716$

  4. $2.525$

Show answer
Correct Option: A
Explanation:

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

Therefore ${ \mu  } _{ glass }{ x } _{ glass }={ \mu  } _{ ruby }{ x } _{ ruby }\ { x } _{ ruby }=\dfrac { { \mu  } _{ glass }{ x } _{ glass } }{ { \mu  } _{ ruby } } =\frac { 1.51\times 2 }{ 1.76 } =1.716$

Consider telecommunication through optical fibres. Which of the following statements is NOT true? 

physics option c: imaging fibre optics basics optical fibre the critical angle, total internal reflection and optical fibre

  1. Optical fobres can be of graded refractive index

  2. Optical fibres are subjected to electromagnetic interference from outside

  3. Optical fibres have extremely low transmission loss

  4. Optical fibres may have homogeneous core with a suitable cladding

Show answer
Correct Option: B

Optical fibre, which is used in communication, works on which principle?

physics option c: imaging fibre optics basics optical fibre the critical angle, total internal reflection and optical fibre

  1. Dispersion

  2. Total Internal reflection

  3. Reflection

  4. Refraction

Show answer
Correct Option: B

Optical fiber communication is based on which of the following phenomena:- 

physics option c: imaging fibre optics basics optical fibre the critical angle, total internal reflection and optical fibre

  1. Total internal reflection

  2. Scattering

  3. Reflection

  4. Interference

Show answer
Correct Option: A

If parabolic profile is used for refractive index in the core, what is the name given to such core?

physics option c: imaging fibre optics basics optical fibre the critical angle, total internal reflection and optical fibre

  1. single mode core

  2. multi mode core

  3. differential mode core

  4. curvilinear differential core

Show answer
Correct Option: D
Explanation:

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 losses in the fiber is due to Raman scattering, polarization and diffraction. The loss due to diffraction can be minimized by using differential cores, that is, by having varying refractive index along the radial direction.
When these cores are parabolic, the loss is least. Such cores are called curvilinear differential cores.