Jkp Constable Telecommunication Telecommunication Mcqs Jkp Constable (1089 MCQs) | JKSSB & SSC Quiz

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Practice Questions

1089 Total
Question 1031 Discuss
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The very high frequency (VHF) band covers the radio spectrum ranging from:

A
3 MHz to 30 MHz
B
30 MHz to 300 MHz
C
300 MHz to 3 GHz
D
3 GHz to 30 GHz

Answer & Explanation

Correct Option: B

By ITU designation, the VHF band ranges from 30 MHz to 300 MHz, widely used for FM radio broadcasting, television, and land mobile stations.
Question 1032 Discuss
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In a basic block diagram of a communication system, the component that introduces the most noise is typically the:

A
Transmitter
B
Modulator
C
Communication Channel
D
Receiver display

Answer & Explanation

Correct Option: C

The communication channel (the physical medium or free space) is exposed to external environmental factors and cross-talk, making it the primary entry point for noise.
Question 1033 Discuss
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For a pure silicon semiconductor at absolute zero temperature (0 Kelvin), the material acts as a:

A
Perfect conductor
B
Superconductor
C
Perfect insulator
D
Variable resistor

Answer & Explanation

Correct Option: C

At absolute zero, intrinsic semiconductors have no thermal energy to break covalent bonds. Consequently, there are no free charge carriers, and it behaves as a perfect insulator.
Question 1034 Discuss
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To achieve proper matching between a 75-ohm coaxial cable and a 300-ohm folded dipole antenna, which device is required?

A
Balun
B
Splitter
C
Amplifier
D
Isolator

Answer & Explanation

Correct Option: A

A Balun (Balanced to Unbalanced) transformer is used to connect an unbalanced line (coax) to a balanced antenna (dipole) while also matching the 1:4 impedance ratio.
Question 1035 Discuss
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In pulse code modulation (PCM), what defines 'Quantization Noise'?

A
Thermal noise generated within the transmitting circuitry
B
Interference from adjacent frequency channels
C
The error introduced between the actual analog value and its assigned discrete digital level
D
Errors resulting from pulse spreading in optical fibers

Answer & Explanation

Correct Option: C

Quantization rounds a continuous analog value to the nearest discrete step. This rounding difference mathematically manifests as quantization error or noise.
Question 1036 Discuss
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When a magnetic field induces eddy currents inside the iron core of an electrical machine, this primarily causes:

A
Increased torque output
B
Heat generation and power loss
C
Improved voltage regulation
D
Faster synchronization speeds

Answer & Explanation

Correct Option: B

Eddy currents are circulating currents induced within the bulk conductive core material. Due to the core's electrical resistance, they dissipate useful energy as I^2R heat loss.
Question 1037 Discuss
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Which of the following is a key reason for using laminations in the armature core of a DC generator?

A
To reduce copper losses
B
To reduce hysteresis losses
C
To reduce eddy current losses
D
To provide mechanical strength

Answer & Explanation

Correct Option: C

Laminating the core drastically increases its electrical resistance in the path of eddy currents, significantly minimizing eddy current power loss without affecting the magnetic flux.
Question 1038 Discuss
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An AM broadcast transmitter radiates 100 kW unmodulated. If the carrier is modulated with a sine wave by 80%, what is the total transmitted power?

A
132 kW
B
164 kW
C
180 kW
D
100 kW

Answer & Explanation

Correct Option: A

Pt = Pc * (1 + m^2/2) = 100 * (1 + 0.8^2/2) = 100 * (1 + 0.64/2) = 100 * 1.32 = 132 kW.
Question 1039 Discuss
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Which component in an optical fiber system transforms electrical signals into optical signals for transmission?

A
Photodiode
B
Avalanche Photodetector
C
Laser Diode or LED
D
Optical Splitter

Answer & Explanation

Correct Option: C

Light Emitting Diodes (LEDs) or Laser Diodes act as light sources. They are modulated by input electrical currents to output corresponding optical pulses.
Question 1040 Discuss
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What is the primary operational advantage of using an 'active' satellite over a 'passive' satellite?

A
Passive satellites are more expensive
B
Active satellites amplify and retransmit the received signal
C
Active satellites do not require solar panels
D
Passive satellites suffer zero latency

Answer & Explanation

Correct Option: B

Active satellites possess transponders that receive, filter, amplify, and translate the frequency of a signal before sending it back down, preventing signal fade-out.
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