Jkp Constable Telecommunication Telecommunication Mcqs Jkp Constable (1089 MCQs)

Question 91 Discuss

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Calculate the skin depth of copper at 100 MHz, given that its skin depth at 1 MHz is 66 micrometers.

A

0.66 micrometers

B

6.6 micrometers

C

66 micrometers

D

660 micrometers

Answer & Explanation

Correct Option: B

Skin depth is inversely proportional to the square root of frequency. D_new = D_old / sqrt(F_new/F_old) = 66 / sqrt(100) = 6.6 micrometers.

Question 92 Discuss

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The relationship between an antenna's Gain (G), Directivity (D), and Radiation Efficiency (e) is given by:

A

G = D / e

B

G = D * e

C

D = G * e

D

G = D + e

Answer & Explanation

Correct Option: B

Gain is the product of Directivity and Radiation Efficiency. If an antenna is 100% efficient, its Gain equals its Directivity.

Question 93 Discuss

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What is the primary purpose of companding (compressing and expanding) in a PCM system?

A

To reduce the required bandwidth

B

To improve the signal-to-quantization noise ratio for weak signals

C

To synchronize the transmitter and receiver

D

To eliminate slope overload

Answer & Explanation

Correct Option: B

Companding amplifies weak signals more than strong ones before quantization, distributing quantization steps non-linearly to favor weak voices.

Question 94 Discuss

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Differential Pulse Code Modulation (DPCM) is more efficient than standard PCM because it:

A

Uses fewer quantization levels for the same signal

B

Transmits only the difference between consecutive samples

C

Samples the signal at half the Nyquist rate

D

Removes the need for a low pass filter

Answer & Explanation

Correct Option: B

Since adjacent samples of analog signals (like voice or video) are highly correlated, sending the difference requires fewer bits than sending absolute values.

Question 95 Discuss

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In standard television broadcasting, approximately what percentage of the total horizontal line time is occupied by the horizontal blanking interval?

A

2%

B

10%

C

18%

D

30%

Answer & Explanation

Correct Option: C

A horizontal line takes 64 microseconds (PAL). About 11-12 microseconds (~18%) of this time is dedicated to the horizontal blanking pulse for retrace.

Question 96 Discuss

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If one of the supply phases of a running 3-phase induction motor is disconnected (single-phasing), what is the immediate effect if it is lightly loaded?

A

The motor stops instantly

B

It continues to run but draws excessive current on the remaining phases

C

It reverses its direction of rotation

D

The slip becomes zero

Answer & Explanation

Correct Option: B

A lightly loaded motor will keep running on single phase due to pulsating torque, but it must draw much higher current from the remaining phases to maintain power, causing severe overheating.

Question 97 Discuss

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A 220V DC shunt motor has an armature resistance of 0.5 ohms. If the motor draws an armature current of 20A, what is the generated back EMF?

A

200 V

B

210 V

C

220 V

D

230 V

Answer & Explanation

Correct Option: B

Eb = V - IaRa = 220 - (20 * 0.5) = 220 - 10 = 210 V.

Question 98 Discuss

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In the SI system, what is the unit of magnetic flux density?

A

Weber

B

Tesla

C

Henry

D

Ampere-turns

Answer & Explanation

Correct Option: B

Magnetic flux density (B) is measured in Tesla (T), which is equivalent to Webers per square meter (Wb/m^2).

Question 99 Discuss

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Under the Information Technology Act 2000 of India, which cryptographic technique is legally recognized for electronic signatures?

A

Symmetric key cryptography

B

Asymmetric crypto system and hash function

C

Steganography

D

Quantum key distribution

Answer & Explanation

Correct Option: B

Section 3 of the IT Act 2000 explicitly provides legal recognition to digital signatures created using an asymmetric (public-key) crypto system and hash function.

Question 100 Discuss

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A power supply yields an output voltage of 12.5V under no-load condition and 12.0V under full-load condition. What is its percentage voltage regulation?

A

4.0%

B

4.16%

C

5.0%

D

10.0%

Answer & Explanation

Correct Option: B

Voltage Regulation = ((Vnl - Vfl) / Vfl) * 100 = ((12.5 - 12.0) / 12.0) * 100 = (0.5 / 12.0) * 100 = 4.16%.

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Practice Questions

Calculate the skin depth of copper at 100 MHz, given that its skin depth at 1 MHz is 66 micrometers.

Answer & Explanation

The relationship between an antenna's Gain (G), Directivity (D), and Radiation Efficiency (e) is given by:

Answer & Explanation

What is the primary purpose of companding (compressing and expanding) in a PCM system?

Answer & Explanation

Differential Pulse Code Modulation (DPCM) is more efficient than standard PCM because it:

Answer & Explanation

In standard television broadcasting, approximately what percentage of the total horizontal line time is occupied by the horizontal blanking interval?

Answer & Explanation

If one of the supply phases of a running 3-phase induction motor is disconnected (single-phasing), what is the immediate effect if it is lightly loaded?

Answer & Explanation

A 220V DC shunt motor has an armature resistance of 0.5 ohms. If the motor draws an armature current of 20A, what is the generated back EMF?

Answer & Explanation

In the SI system, what is the unit of magnetic flux density?

Answer & Explanation

Under the Information Technology Act 2000 of India, which cryptographic technique is legally recognized for electronic signatures?

Answer & Explanation

A power supply yields an output voltage of 12.5V under no-load condition and 12.0V under full-load condition. What is its percentage voltage regulation?

Answer & Explanation

jkp constable telecommunication

Topics

Browse Topics

Practice Questions

Calculate the skin depth of copper at 100 MHz, given that its skin depth at 1 MHz is 66 micrometers.

Answer & Explanation

The relationship between an antenna's Gain (G), Directivity (D), and Radiation Efficiency (e) is given by:

Answer & Explanation

What is the primary purpose of companding (compressing and expanding) in a PCM system?

Answer & Explanation

Differential Pulse Code Modulation (DPCM) is more efficient than standard PCM because it:

Answer & Explanation

In standard television broadcasting, approximately what percentage of the total horizontal line time is occupied by the horizontal blanking interval?

Answer & Explanation

If one of the supply phases of a running 3-phase induction motor is disconnected (single-phasing), what is the immediate effect if it is lightly loaded?

Answer & Explanation

A 220V DC shunt motor has an armature resistance of 0.5 ohms. If the motor draws an armature current of 20A, what is the generated back EMF?

Answer & Explanation

In the SI system, what is the unit of magnetic flux density?

Answer & Explanation

Under the Information Technology Act 2000 of India, which cryptographic technique is legally recognized for electronic signatures?

Answer & Explanation

A power supply yields an output voltage of 12.5V under no-load condition and 12.0V under full-load condition. What is its percentage voltage regulation?

Answer & Explanation

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