Tag: the critical angle, total internal reflection and optical fibre

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Questions Related to the critical angle, total internal reflection and optical fibre

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

Light of different colours propagates through air :

  1. with velocity of air

  2. with different velocity

  3. with velocity of sound

  4. with equal velocity
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation
  • 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
Multiple choice physics option c: imaging fibre optics basics optical fibre the critical angle, total internal reflection and optical fibre

In an optical fibre during transmission of light

  1. Energy increases.

  2. Energy decreases.

  3. No loss of propagation of energy takes place.

  4. Light partially reflects and refracts.
Reveal answer Fill a bubble to check yourself
C Correct answer
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.

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

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

  1. Photoelectric effect

  2. Uncertainty principle

  3. Light diffraction

  4. Light polarization

  5. Total internal reflection
Reveal answer Fill a bubble to check yourself
E Correct answer
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.

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

A cutted diamond sparkles because of its:

  1. high refractive index

  2. hardness

  3. emission of light by the diamond

  4. absorption of light by the diamond
Reveal answer Fill a bubble to check yourself
A Correct answer
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.

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

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 $3\times { 10 }^{ 8 }m/s$.

  1. <div>0.264; $75.{ 3 }^{ 0 }$</div>

  2. <div>0.464; $45.{ 3 }^{ 0 }$</div>

  3. <div>0.364; $25.{ 3 }^{ 0 }$</div>

  4. <div>0.264; $15.{ 3 }^{ 0 }$</div>
Reveal answer Fill a bubble to check yourself
D Correct answer
Explanation

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.

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

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?

  1. $1.716$

  2. $1.525$

  3. $2.716$

  4. $2.525$
Reveal answer Fill a bubble to check yourself
A Correct answer
Explanation

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

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

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

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

  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
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

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