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UGC-NET Electronic Science Question Paper With Answer Key and Full Explanation [2024]

 

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UGC-NET Electronic Science 2024 Answers with Explanations

1.

The peak concentration in the lateral autodoping profile is a function of the following parameters:

(a) Temperature
(b) Surface concentration in the buried layer
(c) Applied voltage
(d) Growth time

Options:

A. (a) and (b) only
B. (a) and (c) only
C. (a), (b) and (c) only
D. (a), (b) and (d) only

Answer: D

2.

A parallel plate capacitive transducer having air as dielectric between the plates, plate area is 50 mm × 50 mm and plate spacing is 0.5 mm. The displacement causes the capacitance to change by 10 pF. The sensitivity of the capacitive displacement transducer is:

A. 50.23 pF/mm
B. 66.67 pF/mm
C. 61.25 pF/mm
D. 59.12 pF/mm

Answer: B

3.

In a charge coupled device, the charge storage and transfer action is controlled by one of the following:

A. Drain Electrode
B. Gate Electrodes
C. Source Electrodes
D. Back of the Substrate

Answer: B

4.

Following set of instructions in 8086 searches a table of 100 bytes for 0AH. Select the correct option: 

MOV CX, 100
MOV AL, 0AH

(a) SCASB
(b) CLC
(c) CLD
(d) REPNE SCASB
(e) JCXZ NOT_FOUND

NOT FOUND : END
A. (a), (d), (b), (e), (c)
B. (b), (d), (a), (e), (c)
C. (c), (d), (a), (e), (b)
D. (b), (d), (c), (e), (a)

Answer: C

5.

The band gap of a semiconductor material that can be considered for making solar cell will be:

A. < 1 eV
B. Between 2 & 3 eV
C. Between 1 & 2 eV
D. > 3 eV

Answer: C

6.

Arrange the following in the decreasing order of their Bandgap (eV) at 300K.

(a) GaAs
(b) Si
(c) Ge
(d) ZnO
(e) InSb

Order: ZnO > GaAs > Si > Ge > InSb

Answer: D

7.

A thyristor having the equivalent capacitance of the depletion layer of reverse biased junction as 20 picofarad can be fired with a dv/dt of 120 V/µsec. The capacitive current flowing through the junction will be:

i = C (dv/dt)

A. 1.8 mA
B. 2.4 mA
C. 3.6 mA
D. 5.9 mA

Answer: B

8.

The circular loop of radius a carries current I. The magnetic field at an observation point in spherical coordinates is asked.



A. Hr = (I Ï€a² cosθ) / (2Ï€ r³)
B. Hr = (I Ï€a² cosθ) / (2Ï€ r²)
C. Hr = (I Ï€a² sinθ) / (2Ï€ r³)
D. Hr = (I Ï€a² sinθ) / (4Ï€ r³)

Answer: A

9.

A PMMC instrument has a three-resistor Ayrton shunt connected in parallel with it to make an ammeter. The current range when connected to terminal C is asked.



A. 10 mA
B. 1 mA
C. 100 mA
D. 1 A

Answer: C

10.

Match the List-I with List-II (Input waveform with Output waveform).



Answer: A


11. Match List-I with List-II (Programmable Logic Devices)

  • (a) PROM
  • (b) PLA
  • (c) PAL
  • (d) EEPROM
Answer: B

(a) → III (AND array fixed, OR programmable)
(b) → I (Both AND and OR programmable)
(c) → IV (AND programmable, OR fixed)
(d) → II (Reprogrammable memory)

12. For microwave sources and devices, identify the correct statements.

Answer: D

Correct statements: (a) and (e).

13. Arrange the following in increasing order of electron mobility at 300 K.

  • (a) Si
  • (b) Ge
  • (c) GaP
  • (d) InAs
Answer: D

Increasing order:
GaP < Si < Ge < InAs

14. Arrange the Z-parameters in descending order.

  • (a) Z11
  • (b) Z21
  • (c) Z12
  • (d) Z22
Answer: B

Descending order:
Z22 > Z11 > Z21 > Z12

15. Match Maxwell’s equations with their integral forms.

Answer: C

(a) → IV
(b) → I
(c) → II
(d) → III

16. Reflection of plane electromagnetic wave at normal incidence.

Answer: D

Er/Ei = ( √ε₁ − √ε₂ ) / ( √ε₁ + √ε₂ )

17. Determine the operating point of the transistor circuit.

Answer: D

Collector current Ic = 1.86 mA
Collector voltage Vc = 6.28 V

18. Why does Si/SiGe HBT have lower cutoff frequency than GaAs and InP HBTs?

Answer: A

Because silicon has lower carrier mobility.

19. Match the control system block diagrams with their equivalent forms.

Answer: B

20. Identify the blocks in the CRO block diagram.

Answer: C

I → Vertical Amplifier
II → Delay Line
III → Trigger Circuit
IV → Time Base Generator
V → Horizontal Amplifier

21. A 6-bit DAC has step size of 50 mV. Find full-scale output and resolution.

Answer: D

Full scale voltage = 3.15 V
Resolution = 1.587%

22. For the control system output:
c(t) = 1 + 0.25e⁻⁵⁰áµ— − 1.25e⁻¹⁰áµ—

Answer: D

Natural frequency = 22.36 rad/s
Damping ratio = 1.34

23. Find the voltage gain of the common source FET circuit.

Answer: B

Voltage gain ≈ −7.9

24. Arrange logic families in increasing order of noise margin.

Answer: A

ECL < IIL < TTL < MOS

25. Arrange sections of a firing pulse generator using inverse cosine control.

Answer: B

Phase shift circuit → Isolating transformer → Level comparator → Clock pulse generator → Flip-flop


26. Match the List-I with List-II (8051 Timer Modes)

List-I (Timer Mode)
  • (a) Mode 0
  • (b) Mode 1
  • (c) Mode 2
  • (d) Mode 3
List-II (Operation)
  • I. 16-bit timer/counter
  • II. Two 8-bit timers
  • III. 13-bit timer/counter
  • IV. Auto-reload of TL from TH

Answer: (a) → III, (b) → I, (c) → IV, (d) → II

27. Shannon Capacity

For a telephone circuit with SNR = 1000 and bandwidth = 2.7 kHz, find the channel capacity.

  • A. 26.9 Kbps
  • B. 2.7 Kbps
  • C. 3.32 Kbps
  • D. 29.6 Kbps

Answer: A (≈ 26.9 Kbps)

28. Satellite Bands

List-I
  • (a) C-Band
  • (b) X-Band
  • (c) Ku-Band
  • (d) Ka-Band
List-II (GHz)
  • I. 7.9–8.4
  • II. 27–30
  • III. 5.9–6.4
  • IV. 14–14.5

Answer: (a) → III, (b) → I, (c) → IV, (d) → II

29. EEG & ECG Matching

List-I
  • (a) Gamma (γ)
  • (b) Theta (θ)
  • (c) QRS interval
  • (d) PR interval
List-II
  • I. 0.1–0.2 s
  • II. 0.05–0.10 s
  • III. 4–8 Hz
  • IV. 22–30 Hz

Answer: (a) → IV, (b) → III, (c) → II, (d) → I

30. Superheterodyne Receiver Sequence

  • (a) Mixer
  • (b) RF stage
  • (c) Antenna
  • (d) Detector
  • (e) IF Amplifier

Correct Sequence:

(c) → (b) → (a) → (e) → (d)

Answer: B

31. Thyristor Matching

List-I
  • (a) BCT
  • (b) RCT
  • (c) ETO
  • (d) TRIAC
List-II
  • I. Bidirectional triggering (Quadrants I & III)
  • II. Turn-on & turn-off control
  • III. Bipolar-controlled thyristor
  • IV. Built-in antiparallel diode

Answer: (a) → III, (b) → IV, (c) → II, (d) → I

32. Segregation Coefficient Order

  • (a) Al
  • (b) As
  • (c) B
  • (d) C
  • (e) P

Answer: (a), (d), (b), (e), (c)

33. Counter Valid States (4-bit)

  • (a) Ring counter
  • (b) Johnson counter
  • (c) Decade counter
  • (d) Ripple counter

Answer: (a) → (b) → (c) → (d)

34. Series RLC Impedance Order

  • (a) ω = 4800 Hz
  • (b) ω = 4000 Hz
  • (c) ω = 3200 Hz
  • (d) ω = 4400 Hz

Answer (Descending |Z|):

(c) > (a) > (d) > (b)

35. Open Loop vs Closed Loop Systems

  • (a) More stable
  • (b) More reliable
  • (c) Easier to build
  • (d) Cannot be optimized (false)

Answer: C — (a) and (c) only

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