JKSSB Electronics MCQs

1. In a BJT transistor a is common base current gain and ẞ is common emitter current gain. What is relation between α and ẞ

A

α = ẞ/(1 - ẞ)

B

α = ẞ/(1 +ẞ)

C

α = ẞ/(ẞ - 1)

D

Relation between α and ẞ depends on circuit

Electronics Statistical Assistant 2025 REPORT ERROR
Correct Answer: B
Explanation:

α = ẞ / (1 + ẞ)

Correct Answered:

Wrong Answered:

2. Match the following Operation Characteristics:

Column - A (Diodes)    Column - B (Characteristics)

i) Zener Diode 1. Negative resistance region due to tunneling

ii) Tunnel Diode 2. Sharp breakdown voltage in reverse bias

iii) Schottky Diode 3. Low forward voltage drop (~0.2-0.3 V)

iv) Varactor Diode 4. Junction capacitance varies with reverse bias

Choose the correct option:

A

i-2, ii-1, iii-3, iv-4

B

i-2, ii-4, iii-1, iv-3

C

i-2, ii-4, iii-1, iv-3

D

i-4, ii-3, iii-2, iv-1

Electronics Statistical Assistant 2025 REPORT ERROR
Correct Answer: A
Explanation:

i-2, ii-1, iii-3, iv-4

Correct Answered:

Wrong Answered:

3. Match bands with uses.

A

1-4,2-3,3-2,4-1

B

1-3,2-4,3-2,4-1

C

1-2,2-3,3-4,4-1

D

1-4,2-2,3-1,4-3

Electronics ? Communication JKP Telcom 2024 REPORT ERROR
Correct Answer: A
Explanation:

Mapping: VHF=TV/FM, UHF=cellular, HF=shortwave, SHF=satellite.

Correct Answered:

Wrong Answered:

4. Composite video signal true?

A

Includes audio, video, sync

B

Contains only video component

C

Uses one sideband only

D

Used only in SHF

Electronics ? TV Systems JKP Telcom 2024 REPORT ERROR
Correct Answer: A
Explanation:

Composite video signal includes video, audio and sync signals.

Correct Answered:

Wrong Answered:

5. Match terms with descriptions.

A

1-1,2-2,3-3,4-4

B

1-2,2-1,3-3,4-4

C

1-3,2-1,3-4,4-2

D

1-4,2-3,3-2,4-1

Electronics ? Communication JKP Telcom 2024 REPORT ERROR
Correct Answer: B
Explanation:

Correct mapping: Progressive=scan sequence, SSB=one sideband, UHF=300MHz-3GHz, Negative pulses=darker area.

Correct Answered:

Wrong Answered:

6. Interlaced scanning in picture tube means

A

Top to bottom one pass

B

Odd lines then even lines

C

All lines at once

D

Half lines in passes

Electronics ? TV Systems JKP Telcom 2024 REPORT ERROR
Correct Answer: B
Explanation:

Interlaced scanning scans odd then even lines.

Correct Answered:

Wrong Answered:

7. SSB-SC generated by ____ methods.

A

Phase

B

Frequency

C

Both

D

None

Electronics ? Modulation JKP Telcom 2024 REPORT ERROR
Correct Answer: C
Explanation:

SSB-SC can be generated by both phase and filter methods.

Correct Answered:

Wrong Answered:

8. Match Medium type with Frequency:

1.Open wire    i.100kHz 

2.Twisted pair    ii.100MHz 

3.Coaxial cable.     iii.5kHz.

A

1-3,2-1,3-2

B

1-2,2-3,3-1

C

1-1,2-3,3-2

D

1-2,2-1,3-3

Electronics ? Communication JKP Telcom 2024 REPORT ERROR
Correct Answer: A
Explanation:

Open wire=5kHz, Twisted pair=100kHz, Coaxial=100MHz.

Correct Answered:

Wrong Answered:

9. For dipole antenna, which true?

A

Uniform current distribution

B

Effective length=3?physical length

C

Radiation max ? to axis

D

Impedance independent

Electronics ? Antenna JKP Telcom 2024 REPORT ERROR
Correct Answer: C
Explanation:

Radiation max normal to dipole axis.

Correct Answered:

Wrong Answered:

10. Colour TV signal is

A

Single-channel 1D

B

3-channel 3D

C

3-channel 1D

D

Single-channel 3D

Electronics ? TV Systems JKP Telcom 2024 REPORT ERROR
Correct Answer: C
Explanation:

Colour TV uses 3 colour channels, one dimensional.

Correct Answered:

Wrong Answered:

11. In TV transmission picture=AM, sound=FM. Reason?

A

Bandwidth minimized

B

FM less noise

C

Synchronization easier

D

None

Electronics ? TV Systems JKP Telcom 2024 REPORT ERROR
Correct Answer: B
Explanation:

FM sound less noise prone.

Correct Answered:

Wrong Answered:

12. Match with frequency ranges.

A

2-1,3-2,1-3

B

3-1,2-2,1-3

C

2-3,1-2,3-1

D

2-2,3-3,1-1

Electronics ? Communication JKP Telcom 2024 REPORT ERROR
Correct Answer: A
Explanation:

AF=20Hz-20kHz, IF=10-108MHz, RF=3kHz-300GHz.

Correct Answered:

Wrong Answered:

13. Match modulation with disadvantages:

A

1-1,2-2,3-3,4-4

B

1-4,2-1,3-2,4-3

C

1-3,2-1,3-4,4-2

D

1-2,2-3,3-4,4-1

Electronics ? Modulation JKP Telcom 2024 REPORT ERROR
Correct Answer: B
Explanation:

Superhet=image freq, FM=threshold, PCM=quantization, Delta=granular.

Correct Answered:

Wrong Answered:

14. Matched filter in communication receiver statements?

A

I & II only

B

III & IV only

C

II,III only

D

I,II,III,IV

Electronics ? Filters JKP Telcom 2024 REPORT ERROR
Correct Answer: D
Explanation:

All given properties true.

Correct Answered:

Wrong Answered:

15. Main function of RF amplifier in superhet receiver?

A

Adjacent channel rejection

B

Improved tracking

C

Increase tuning range

D

Reject image frequency

Electronics ? Communication JKP Telcom 2024 REPORT ERROR
Correct Answer: D
Explanation:

RF amplifier helps reject image frequencies.

Correct Answered:

Wrong Answered:

16. AM carrier 15kV at 1 MHz, modulation index=0.8. Peak voltage?

A

18kV

B

12kV

C

18.75kV

D

22kV

Electronics ? Modulation JKP Telcom 2024 REPORT ERROR
Correct Answer: D
Explanation:

Vmax=Vc(1+m)=15(1+0.8)=27kV. Closest 22kV.

Correct Answered:

Wrong Answered:

17. Which mode uses reflecting surface of ionosphere?

A

Ground wave

B

Space wave

C

Sky wave

D

LOS wave

Electronics ? Propagation JKP Telcom 2024 REPORT ERROR
Correct Answer: C
Explanation:

Sky wave propagation uses ionosphere reflection.

Correct Answered:

Wrong Answered:

18. NOT a method for generating FM?

A

Varactor diode

B

Reactance modulator

C

Armstrong modulator

D

By-pass modulator

Electronics ? Modulation JKP Telcom 2024 REPORT ERROR
Correct Answer: D
Explanation:

By-pass modulation is not a method.

Correct Answered:

Wrong Answered:

19. Correct sequence of subsystems in FM receiver?

A

Mixer-RF-Limiter-IF-Discriminator-Audio

B

RF-Mixer-Limiter-Discriminator-IF-Audio

C

RF-Amplifier-Mixer-IF-Amplifier-Limiter-Discriminator-Audio Amplifier

D

Mixer-IF-Amplifier-Limiter-Audio-Discriminator

Electronics ? Communication JKP Telcom 2024 REPORT ERROR
Correct Answer: C
Explanation:

Standard FM superhet receiver sequence.

Correct Answered:

Wrong Answered:

20. In AM, modulation index should be high because?

A

Both statements true

B

Both individually true but II not explanation of I

C

I true, II false

D

I false, II true

Electronics ? Modulation JKP Telcom 2024 REPORT ERROR
Correct Answer: A
Explanation:

Higher modulation index increases power in sidebands.

Correct Answered:

Wrong Answered:

21. What is the transmission frequency range of FM radio?

A

28-56 MHz

B

88-108 MHz

C

58-88 MHz

D

108-128 MHz

Electronics ? Communication JKP Telcom 2024 REPORT ERROR
Correct Answer: B
Explanation:

FM radio operates in the frequency range 88-108 MHz.

Correct Answered:

Wrong Answered:

22. Common use of Band Pass Filter in Radio?

A

Allows specific range

B

Allows all

C

Blocks all

D

Amplifies all

Electronics ? Filters JKP Telcom 2024 REPORT ERROR
Correct Answer: A
Explanation:

Band pass filter selects a specific frequency range.

Correct Answered:

Wrong Answered:

23. Incorrect statement about SMPS

A

Less sensitive to input variations

B

Smaller size compared to rectifiers

C

Has low input ripple

D

Source of radio interference

Electronics ? Power Supplies JKP Telcom 2024 REPORT ERROR
Correct Answer: C
Explanation:

SMPS has high ripple compared to linear supplies.

Correct Answered:

Wrong Answered:

24. Amplitude modulation signal without carrier is known as

A

SSB-SC

B

DSB-SC

C

Both A & B

D

None

Electronics ? Modulation JKP Telcom 2024 REPORT ERROR
Correct Answer: B
Explanation:

Double Sideband Suppressed Carrier (DSB-SC) has no carrier.

Correct Answered:

Wrong Answered:

25. Pulse amplitude modulation is a process whereby

A

Position of pulse is changed

B

Width of pulse varies

C

Height of pulse ? sampled value

D

None of the above

Electronics ? Modulation JKP Telcom 2024 REPORT ERROR
Correct Answer: C
Explanation:

PAM uses pulse amplitude proportional to sample.

Correct Answered:

Wrong Answered:

26. FM to AM conversion: input of FM signal converted into amplitude signal by

A

Differentiator

B

Integrator

C

Demodulator

D

None of the above

Electronics ? Modulation JKP Telcom 2024 REPORT ERROR
Correct Answer: A
Explanation:

FM to AM conversion requires differentiator.

Correct Answered:

Wrong Answered:

27. Upper and lower sideband for AM of 35 kHz with 5 kHz carrier?

A

42.5 kHz & 37.5 kHz

B

45 kHz & 35 kHz

C

50 kHz & 30 kHz

D

25 kHz & 15 kHz

Electronics ? Modulation JKP Telcom 2024 REPORT ERROR
Correct Answer: A
Explanation:

Sidebands=fc?fm=35?7.5=42.5 & 27.5. Closest option A.

Correct Answered:

Wrong Answered:

28. In time-division multiplexing, each multiplexed signal occupies

A

A Fraction of Transmission Bandwidth

B

The Entire Transmission Bandwidth

C

A Bandwidth equal to each input signal

D

None of the above

Electronics ? Communication JKP Telcom 2024 REPORT ERROR
Correct Answer: A
Explanation:

In TDM, each signal uses a fraction of bandwidth but different time slots.

Correct Answered:

Wrong Answered:

29. A PAM signal can be demodulated using

A

High pass filter

B

Band pass filter

C

Low pass filter

D

None of the above

Electronics ? Communication JKP Telcom 2024 REPORT ERROR
Correct Answer: C
Explanation:

Pulse Amplitude Modulated signals are recovered using a low-pass filter.

Correct Answered:

Wrong Answered:

30. In T.V., the picture signal is

A

Amplitude modulated and at the low-frequency end of each channel allocation

B

Frequency modulated and at the low-frequency end of each channel allocation

C

Amplitude modulated and at the high frequency end of each channel allocation

D

None of the above

Electronics ? TV Systems JKP Telcom 2024 REPORT ERROR
Correct Answer: A
Explanation:

Picture signal in TV is amplitude modulated at low-frequency end.

Correct Answered:

Wrong Answered:

31. In television, 4:3 represents?

A

Interlace Ratio

B

Max Horizontal Deflection

C

Aspect Ratio

D

Diagonal Ratio

Electronics ? Television JKP Telcom 2024 REPORT ERROR
Correct Answer: C
Explanation:

4:3 is aspect ratio of TV screens.

Correct Answered:

Wrong Answered:

32. Modulator stage in radio transmitter normally?

A

Class-C Amplifier

B

Class-B push-pull Amplifier

C

Class-A Amplifier

D

Class-D Amplifier

Electronics ? Communication JKP Telcom 2024 REPORT ERROR
Correct Answer: A
Explanation:

Class-C amplifier is used for modulation in transmitters.

Correct Answered:

Wrong Answered:

33. Energy bands: completely filled bands = __, bands with higher energies = __.

A

Conduction, valence

B

Valence, conduction

C

Valence, drift

D

None

Electronics ? Solid State Physics J.E Civil (SD) 2025 REPORT ERROR
Correct Answer: B
Explanation:

Filled bands at 0K = valence; higher = conduction.

Correct Answered:

Wrong Answered:

34. Match List-I (Materials) with List-II (Type): i. Copper ii. Silicon iii. Silicon+P iv. Silicon+Al. Types: 1. Conductor 2. P-type 3. N-type 4. Intrinsic. Choose correct.

A

(i)-1, (ii)-4, (iii)-3, (iv)-2

B

(i)-2, (ii)-3, (iii)-1, (iv)-4

C

(i)-3, (ii)-2, (iii)-1, (iv)-4

D

(i)-4, (ii)-1, (iii)-2, (iv)-3

Electronics ? Semiconductors J.E Civil (SD) 2025 REPORT ERROR
Correct Answer: A
Explanation:

Copper = conductor; Silicon = intrinsic; P-doping = N-type; Al-doping = P-type.

Correct Answered:

Wrong Answered:

35. Hall effect principle applied in: 1. Magnetic field sensing 2. Current measurement 3. Hall effect sensors 4. Linear/angular displacement. Which are correct?

A

1,2

B

2,3

C

1,2,3

D

1,2,3,4

Electronics ? Hall Effect J.E Civil (SD) 2025 REPORT ERROR
Correct Answer: D
Explanation:

Hall effect is applied in all listed areas.

Correct Answered:

Wrong Answered:

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