# Fiber optic communication system MCQ with answers - Part 1

This sets of mcq's most focuses on fiber optics communication system with answers for preparing online and objectives exams...

1. Fiber optic deals with ____
2. Propagation of light
3. Propagation of water
4. Propagation of air
5. All of above

Ans – A

Explanation: -  Fiber optic deals with Propagation of light through transparent dielectric waveguide. Fiber optic used for transmission of data from point to point location.

1. Which semiconductor laser used by first generation of light wave?
1. GaSi
2. SiGa
3. GaAs
4. AsGa

Ans – C

Explanation:- The first generation of light wave uses GaAs semiconductor laser and operating region was near 0.8 µm. Other specifications of this generation are having bit rate of 54 Mb/s and repeater spacing of 10km.

1. What is the bit rate of second generation of light wave?
1. 100 mb/s to 1.7Gb/s
2. 90 mb/s to 1.7Gb/s
3. 10 mb/s to 1Gb/s
4. 20 mb/s to 2Gb/s

Ans – a

Explanation:- bit rate of second generation of light wave is 100 mb/s to 1/.7 Gb/s

1. How many generations of light wave communication?
1. 1
2. 2
3. 4
4. 5

Ans –d

Explanation:- There are total 5 generation of light wave systems in fiber optics.

1. Light wave occupies the frequency range between ____ to ___Hz.
1. 2 × 1012  to 3.7 × 1012  Hz
2. 1 × 1012  to 3 × 1012  Hz
3. 3 × 1012  to 7 × 1012  Hz
4. 2 × 1012  to 4 × 1012  Hz

Ans – a

Explanation:- Light wave occupies the frequency range between 2 × 1012  to 3.7 × 1012  Hz. Thus information carrying capacity of fiber optic cables is much higher.

1. Fiber optic cables offers very ____ signal attenuation over long distance.
1. High
2. Less
3. Both
4. None

Ans – b

Explanation:- Fiber optic cables offers very less signal attenuation over long distance. It is less than 1 Db/km . This enables longer distance between repeaters.

1. Which of this are advantages of optical fiber communication system?
1. Wide bandwidth
2. Low losses
3. Inference immune
4. All of above

Ans –D

Explanation:- This all three are the advantages of fiber optic communication system.

1. From which component fiber optics made?
1. Copper and aluminium
2. Silica glass and plastic
3. Aluminium
4. None

Ans – b

Explanation:- Fiber cables are made from silica glass and plastic which is lighter than copper and aluminium cables. And lightweight fiber are cheaper to transport.

1. Which of the following is disadvantage of optical fiber communication system?
1. Long distance transmission
2. Security
3. More strength
4. High initial cost

Ans – d

Explanation:- The initial cost of installation or setting up cost is very high compared to all other system. And other three options are advantages.

1.  Telephone networks is the applications of optical fiber communication system.
1. True
2. False

Ans – a

Explanation:- Optical waveguide has low attenuation, high transmission bandwidth compared to copper lines, therefore numbers of long co-axial links between telephone are being replaced by optical fiber.

1. Transmitter, information channel and receiver are basic blocks of fiber optic communication system.
1. True
2. False

Ans – a

Explanation:- True; This three are blocks of optical fiber communication system.

1. Message origin block in transmitter of fiber optic communication system is used for?
1. Converting non-electrical message into electrical signal.
2. Converting electrical message into non-electrical signal
3. Both
4. None

Ans – a

Explanation:- Message origin is from transducer that converts non-electrical message to electrical signal. Examples microphones for converting sound waves into currents and video for converting images into current.

1. Which source generates the wave on which the information is transmitted.
1. Carrier source
2. Modulator
3. Channel coupler
4. None

Ans – a

Explanation:- Carrier source generates the wave on which the information is transmitted. This wave is called carrier.

1. Which diodes is used for fiber optic system?
1. Laser diode (LD) & Light emitting diode (LED)
2. Only LED
3. Only LD
4. None

Ans – a

Explanation:- Laser diode and light emitting diode both are used for fiber optic system. They can be called as optic oscillators, they provide stable, single frequency waves with sufficient power for long distance propagation.

1. What is the use of channel coupler in fiber optic communication system?
1. Coupler feeds the power into the information channel
2. Converting electrical message into proper format
3. Coupler for high losses
4. All of the above

Ans – a

Explanation:- Coupler feeds the power into the information channel. For an atmospheric optic system the channel coupler is a  lens used for collimating the light emitted by the source and directing this light towards the receiver.

1. Information channel is the path between the ___ and ___.
2. Modulator & coupler
3. Transmitter & transmitter

Ans – a

Explanation:- Information channel is the path between transmitter and receiver.

1. BER stands for
1. Bit error rate
3. Byte error rate
4. Bit error rule

Ans – a

Explanation:- BER stands for bit error rate