| 1 |
Crystal lattice is a repetition of |
Atoms
Molecules
Unit cell
All of them
|
| 2 |
Unit cell has a basic structure of |
One dimensional
Two dimensional
Three dimensional
None of these
|
| 3 |
The polymeric solids have specific gravity compared with even the lightest of metals |
Low
Very Low
Slightly low
None of these
|
| 4 |
Polymeric solids have the structure |
One dimensional
Two dimensional
Zero dimension
Three dimensional
|
| 5 |
Polymeric solids have the properties like |
No definite shape
No definite structure
Partially crystalline solids
All of them
|
| 6 |
The amorphous material (solids) have |
No structure
No melting point
No definite shape
All of them
|
| 7 |
On heating, it becomes a very viscous liquid at almost |
500 C<sup>o</sup>
800 C<sup>o</sup>
900 C<sup>o</sup>
1000 C<sup>o</sup>
|
| 8 |
Amorphous materials have the properties of solids like |
No structure
Like liquid
Glassy
a and c
|
| 9 |
Every crystalline solid has a melting point |
Definite
Not definite
Any
Change every time
|
| 10 |
At higher temperature their vibrations become so great that structure suddenly breaks up and changes into |
Order to disorder
Solid into liquid
Melted
All of them
|
| 11 |
Inspite vibrations the force which hold the atoms in their ordered form is |
Vander vall force
Cohesive force
Adhesive force
None of these
|
| 12 |
While vibrating the atoms are at their |
Fixed positions
Extreme position
Average positions
None of these
|
| 13 |
With the rise of temperature the amplitude of atoms |
Slow down
Fixed
Increases
None of these
|
| 14 |
The atoms molecules or ions in a crystalline solids are at room temperature |
Motionless
Vibrate violently
Fixed
Simply vibrate
|
| 15 |
The metals become a magnetic material because of their |
Hardness
Alignment of atoms
Structure
All of them
|
| 16 |
The metals become electrically conducting due to their |
Ductility
Hardness
Structure
All of them
|
| 17 |
Crystalline solids are also |
Metals
Ionic compound
Ceramics
All of them
|
| 18 |
Crystalline solids have the properties such as |
Regular arrangement
Covalent bonding
Some what defective
All of them
|
| 19 |
The re conversion of light signals into electrical signals takes place due to |
Transmitter
Receiver
Generator
None of these
|
| 20 |
The conversion of electrical signals into light signals taken place due to |
Generator
Transmitter
Receiver
None of these
|
| 21 |
In digital modulation, the LED or laser flashed on and off at a |
Fast rate
Very fast rate
Extremely fast rate
None of these
|
| 22 |
Using a graded index fibres the time difference is reduced to about |
0.5 ns per km
1.0 ns per km
2.0 ns per km
2.3 ns per km
|
| 23 |
Inspite of different dispersion, all the wavelengths arrive at the other end of the fibre at the same time. With a step-index fibre overall time difference may be about |
40 ns
30 ns
32 ns
33 ns
|
| 24 |
The power loss can also take place due to |
Information received can be inaccurate due to dispersion
Light signal may not be perfectly monochromatic
Signal accuracy may be affected by deflective source
All of these
|
| 25 |
Power loss taken place when a light signal travels along fibres by |
Multiple reflection
Light absorbed due to impurities in glass
At joint some light is scattered by group of atoms
All of these
|
| 26 |
Which device converts the light signals which these amplified and decoded |
Photo cell
Photo diode
Photo transistor
None of these
|
| 27 |
In a never system, the repeaters are placed at about |
50 km
75 km
100 km
125 km
|
| 28 |
Repeaters are the devices which regenerate the signals and are placed at about |
20 km
30 km
40 km
50 km
|
| 29 |
The ultra-purity of optical fibre is |
90 %
99 %
99.9 %
99.99 %
|
| 30 |
The digital modulation is expressed in |
Bytes
Codes
Bits
None of these
|
| 31 |
The transmission of information by light waves may be |
An audio signal
A television signal
A computer data signals
All of them
|
| 32 |
Which one light source can travel faster through optical fibre is |
Infra red
Visible
Ultra violet
All of these
|
| 33 |
The typical wavelength of light source in transmitter is |
1.1 μm
1.2 μm
1.3 μm
1.4 μm
|
| 34 |
The light source in the transmitter can be either |
Light emitting diode
Semiconductor laser
Light emitting in an invisible infra red
All of these
|
| 35 |
The components of a fibre optic communication system is/are |
At transmitter
An optical fibre
Receiver
All of these
|
| 36 |
How many major components of fibre optic communication system are |
4
5
3
2
|
| 37 |
When refractive index of core is 1.50 and of 1.48 of cadding then find the angle of entry for an optical fibre is |
11.2<sup>o</sup>
14.2<sup>o</sup>
15.4<sup>o</sup>
13.6<sup>o</sup>
|
| 38 |
Calculate the critical angle when core refractive index is 1.50 and cladding of refractive index 1.48 |
70.3<sup>o</sup>
80.9<sup>o</sup>
80.6<sup>o</sup>
89.6<sup>o</sup>
|
| 39 |
In multimode graded index fibre core and cladding has boundary |
Noticeable
No noticeable
No boundary
None of these
|
| 40 |
The range of the diameter of core in multimode graded index fibre is |
50 to 100 μm
50 to 1000 μm
50 to 1000 μm
None of these
|