| 1 |
The lower refractive index the fibre core has |
1.48
1.40
1.54
1.42
|
| 2 |
The fibre core has constant refractive index such as |
1.48
1.5
1.52
1.56
|
| 3 |
Due to dispersion effects, white light source is useful for |
Long distance
Short distance
Very long distances
None of these
|
| 4 |
The light source used in multimode step index fibre is |
A monochromatic source
Red light
White light
None of these
|
| 5 |
Multimode step index fibre has diameter as |
40 μm
50 μm
60 μm
None of these
|
| 6 |
A single step index fibre can carry more than |
14 TV channels
14,000 phone calls
16 TV channels
a and b
|
| 7 |
The light signals are sent from the source |
A ordinary source
A monochromatic light source
A moulticolour source
None of these
|
| 8 |
Single mode step index fibre has feature/s like |
Very thin core
5 (μm) miameter
Relatively large cladding
All of these
|
| 9 |
How many types of the optical fibres are |
One
Two
Three
Four
|
| 10 |
A new type of optical fibre in which central core has high refractive index and its density gradually decreases towards its periphery is called |
Step index fibre
Multimode step index fibre
Multimode graded index
None of these
|
| 11 |
Such type of fibre in which center core is of high refractive index and the layer over the central core is low refractive index is called |
Step index fibre
Multi mode step index fibres
Multimode graded index fibre
None of these
|
| 12 |
The optical fibre has a layer over the central layer is called cladding of refractive index |
High
Low
Very high
None of these
|
| 13 |
Two layers optical fibre in which central layer is called core which has refractive index |
High
Low
Very low
None of these
|
| 14 |
A mode of propagation of light through optical fibre in which the light within the fibre is |
Reflected
Refracted
Continuously refracted
None of these
|
| 15 |
The total internal reflection takes place for glass-air boundary is then the angle is |
Equal to 41.8<sup>o</sup>
Greater than 41.8<sup>o</sup>
Less than 41.8<sup>o</sup>
None of these
|
| 16 |
For glass-air boundary the critical angle θc is |
30<sup>o</sup>
41.8<sup>o</sup>
42.0<sup>o</sup>
44.0<sup>o</sup>
|
| 17 |
Snell's Law is defined as |
n1 sin θ<sub>2</sub> = n<sub>2</sub> sin θ
n sin θ<sub>1</sub> = n<sub>1</sub> sin θ<sub>2</sub>
n<sub>1</sub> sin θ<sub>1</sub> = n<sub>2</sub> sin θ<sub>2</sub>
None of these
|
| 18 |
If the angle of refraction is 90o, for which the angle of incidence is called |
Incident angle
Critical angle
Angle of emergence
None of these
|
| 19 |
Propagation of light in an optical fibre requires |
Total internal reflection
Continuous refraction
Both
None of these
|
| 20 |
Proportion of light in an optical fibre requires that the light-should be within the fibre |
Very little confined
Largely confined
Totally confined
None of these
|
| 21 |
An optical fibre with its protective case may be typically 6.0 mm in diameter and yet it can replace bundle of copper of diameter |
6.79 cm
6.95 cm
7.52 cm
7.62 cm
|
| 22 |
Characteristics of optic fibre is/are |
Much thineer
Light weight
Extremely wide bandwidth
All of these
|
| 23 |
The practical use of services by optic fiber is |
Two way television
World processing
Image transmitting and receiving equipment
All of these
|
| 24 |
With tremendous information carrying capacity is called |
Data entry
Band width
Word processing
None of these
|
| 25 |
Fire optics has ability to transmit |
Thousand telephone conversation
Several television programs
Numerous data signals between stations
All of these
|
| 26 |
Fiber optics also used to transmit light |
Around corners
Into inaccessible place
Formerly unobservable objects
All of these
|
| 27 |
The advantage/advantages of fiber optics than radio wave carriers |
Much wider band width
Capability
Immunity
All of these
|
| 28 |
In photo phone modulated beam of reflected sun light focused on a detector several hundred meters away with the divice |
Germanium
Selinium
Silicon
None of these
|
| 29 |
Graham Bell photo phone used a modulated beam of |
Reflected sun light
Refracted sun light
Diffracted sun light
None of these
|
| 30 |
Photo phone was invented by |
Edison
Graham Bell
Bardeen
None of these
|
| 31 |
The resolution of microscope depends on objective's |
Focal length
Material
Diameter
None of these
|
| 32 |
A wider objective and the use of blue light of short wavelength produces |
Interference
Diffraction
Less diffraction
Polarization
|
| 33 |
An image formed by a concave lens is always |
Virtual
Real
Inverted
None of these
|
| 34 |
A double convex lens acts as a diverging lens when the object is |
Between f and 2f
At the foucs
Inside the focus
All of these
|
| 35 |
The minimum distance between an object and its image in a convex lens is |
2 f
2.5 f
3 f
3.5 f
|
| 36 |
The speed of light in other material is always |
Greater than c
Less than c
Equal to c
None of these
|
| 37 |
The time taken by light for its passage from M to m and back is |
2c/d
d/2c
2d/c
d<sup>2</sup>/2c
|
| 38 |
The time taken by the mirror M to rotate through an angle 2π/8 is |
1/8 f
1/16 f
1/4 f
1/2 f
|
| 39 |
Angle subtended by any side of the eight-sided mirror at the center is |
π/8
π/4
2π/8
2π/4
|
| 40 |
At certain speed, the time taken by light in moving from M to m and back to M is equal to the time taken by |
Face 4 to 1
Fact 6 to 1
Face 3 to 1
Face 2 to 1
|