UKPSC Deputy Superintendent of Police (Police Telecom) 2025: Electronics and Communication
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SECTION – A
1. Which of the following is not a method to grow crystals ?
(a) Czochralski method (b) Bridgman method
(c) Liquid Phase Copernicus method (d) Liquid Encapsulated Czochralski method
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2. An astable multivibrator is a
(a) square wave generator (b) triangular wave generator
(c) sinusoidal wave generator (d) saw-tooth wave generator
3. Which of the following is not infinity for an ideal operational amplifier ?
(a) Input impedance (b) Output impedance
(c) Frequency bandwidth (d) Open loop gain
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4. For an amplifier having gain A and feedback ratio , the Barkhausen criteria for sustained
oscillations is
(a) A = 0.11 (b) A = 0.33 (c) A = 0.66 (d) A = 1.00
5. The voltage that start an oscillator is caused by
(a) Ripple from the power supply (b) Noise voltage in resistor
(c) The input signal from a generator (d) Positive feedback
6. The Wein-bridge oscillator is useful
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(a) at low frequencies (b) at high frequencies
(c) with LC tank circuits (d) at small input signals
7. The output waveform of a 555 timer is
(a) sinusoidal (b) triangular (c) rectangular (d) elliptical
8. The voltage gain of an op-amp is unity at the
(a) Cut-off frequency (b) Unity-gain frequency
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(c) Generator frequency (d) Power bandwidth
9. The Noise temperature in an communication system is 4306 K, find the noise figure.
(Given : log 15.848 = 1.199)
(a) 3 dB (b) 6 dB (c) 12 dB (d) 24 dB
10. A memoryless source emits message m1 & m2 with probabilities 0.8 and 0.2, respectively.
Find the code efficiency if the source symbols are coded using Hofmann coding for its
second order extension.
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(a) 0.923 (b) 0.815 (c) 0.627 (d) 0.312
11. Satellite used for intercontinental communications are known as
(a) DOSAT (b) COMSAT PEC_Set-A
(c) MARISAT (d) INTELSAT
12. Quantization noise occurs in
(a) TDM (b) FDM (c) PWM (d) PCM
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13. A satellite orbiting in a 600 km orbit transmits 4 GHz frequency. The Doppler shift observed
at the ground station when the satellite is overhead the station is
(a) zero (b) maximum (c) infinity (d) None of the above
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14. A discrete memoryless source emits source symbols X1, X2, X3 & X4 with probabilities
1 1 1 1
P(X1) = , P(X2) = , P(X3) = and P(X4) = . Find the entropy of the system.
2 2 8 8
(a) 1.75 symbols per second (b) 1.75 bits per symbol
(c) 1.25 symbols per second (d) 1.25 bits per second
15. Among these which noise greatly affects the communication system at high frequency ?
(a) Shot noise (b) Impulse noise (c) Transit time noise (d) Random noise
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16. A message signal m(t) = 2 cos (2000 t) + 4 cos (4000 t) modulates the carrier
c(t) = cos (2 fct), where fc = 1 MHz to produce an AM signal. For demodulating the
generated AM signal using an envelope detector, the time constant RC of the detector circuit
should satisfy
(a) 1 s << RC < 0.5 ms (b) 0.5 ms < RC < 1 ms
(c) RC << 1 s (d) RC >> 0.5 ms
17. The signal cos(wct) + 0.5 cos(wmt) sin(wct) is
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(a) FM only (b) AM only
(c) Both FM and AM (d) Neither FM nor AM
18. An AM wave with modulation index 0.8 has a total sideband power of 4.85 kW. The carrier
power and the total power radiated will be nearly
(a) 12.2 kW and 20 kW (b) 15.2 kW and 20 kW
(c) 12.2 kW and 25 kW (d) 15.2 kW and 25 kW
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19. If bandwidth is of primary concern, which of the following schemes is generally not
considered ?
(a) PSK (b) ASK (c) DPSK (d) FSK
20. A continuous time function x(t) is periodic with period T. The function is sampled uniformly
with a sampling period TS. In which of the following cases is the sampled signal periodic ?
(a) T = 2 TS (b) T = 1.2 TS (c) Always (d) Never
21. For a signal with center frequency (fc) of 1200 MHz and bandwidth of 100 MHz, which of
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the following sampling frequency (fs) will cause spectrum inversion ?
(a) 287.5 MHz (b) 575 MHz (c) 1150 MHz (d) 1600 MHz
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22. Coherent demodulation of FSK signal can be effected using
(a) Correlation receiver (b) Bandpass filter and envelope detectors
(c) Matched filter (d) Discriminator detector
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23. What is the required bandwidth of a PCM system for 128 quantization levels when 48
telephone channels, each band limited to 4 KHz, are to be time division multiplexed by this
PCM ?
(a) 2.688 MHz (b) 4.032 MHz (c) 5.376 MHz (d) 1.344 MHz
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24. The modulation scheme commonly used for transmission from GSM mobile terminals is
(a) 4-QAM
(b) 16-PSK
(c) Walsh-Hadamard Orthogonal Codes
(d) Gaussian Minimum Shift Keying (GMSK)
25. The maximum length of a PN sequence, a linear shift register can produce is
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(a) 2m (b) m (c) 2m (d) 2m – 1
26. Which of the following problem occurs due to adjacent channel interference ?
(a) Cross-talk (b) Near-far effect (c) Blocked calls (d) Missed calls
27. GPRS has following protocol
(a) Circuit switched (b) Packet switched
(c) Both (a) and (b) (d) None of these
28. In a cellular network, widely accepted cell shape is
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(a) hexagonal (b) circular
(c) triangular (d) None of the above
29. Wi-Fi is primarily developed for which of the following ?
(a) WLAN (b) LAN (c) WMAN (d) MAN
30. IEEE 802.16 supports which of the following duplexing scheme ?
(a) TDD (b) FDD (c) Both TDD & FDD (d) None of these
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31. A direct sequence BPSK system is used to transmit a voice signal, which is sampled at
8 KHz and encoded using 8 bit PCM format. Let the available carrier frequency is 1.9 GHz
and available bandwidth is 40 MHz. Find the achievable processing gain and maximum chip
rate of the system.
(a) 3125, 128 KHz (b) 62.5, 40 MHz
(c) 12.5, 64 KHz (d) 312.5, 20 MHz
32. A transmission line having a gain of 10 dB, is feeding 1 watt of power to horn antenna. The
antenna is matched to the transmission line. The total power radiated will be
(a) 0.1 watt (b) 10 watt PEC_Set-A(c) 1 watt (d) 0.01 watt
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33. Find the input impedance of a short circuited transmission line. If its characteristic
impedance is 50 and input impedance of open circuited transmission line is
ZOC = 100 + j150
(a) 100 + j150 (b) 50 (c) 7.69 – j11.54 (d) 7.69 + j11.54
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34. A quarter wave transformer can be used for matching accurately
(a) capacitive loads only (b) purely resistive loads only
(c) inductive loads only (d) loads with any nature of reactance
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35. A Yagi antenna has a driven antenna _________.
(a) with a reflector and one or more directors (b) only
(c) with a reflector (d) with one or more directors
36. The radiation field of an antenna at a distance r varies as
1 1 1 1
(a) (b) 2 (c) 3 (d)
r r r r4
37. The Voltage Standing Wave Ratio (VSWR) lies in the range of
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(a) 0 to 1 (b) –1 to +1 (c) 0 to (d) 1 to
38. Select among following, the best application of vertical MAST antenna.
(a) RADAR (b) TV transmission
(c) MW broadcasting (d) TV reception
39. “Double Minimum” method is used to measure
(a) low VSWR (b) high VSWR
(c) low attenuation co-efficient (d) high attenuation co-efficient
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40. A coaxial RF cable has characteristic impedance of 50 and capacitance of 40 pF/m. Find
the inductance per meter.
(a) 10 H/m (b) 1 H/m (c) 0.1 H/m (d) 0.01 H/m
41. A silica optical fiber with a core diameter large enough to be considered by ray theory
analysis has a core refractive index of 1.50 and a cladding refractive index of 1.47. The value
of acceptance angle in air for the fiber is
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(a) 34.1 (b) 69.1 (c) 24.5 (d) 17.4
42. A graded index fiber has a core with a parabolic refractive index profile which has a diameter
of 50 m. The fiber has a numerical aperture of 0.2. What will be the total number of guided
modes propagating in the fiber when it is operating at a wavelength of 1 m ?
(a) 396 (b) 247 (c) 212 (d) 302
43. The value of fiber core diameter for a single mode step index fiber which has an MFD of
11.6 m when the normalized frequency is 2.2, given by
(a) 4.95 m (b) 3.75 m (c) 9.9 m (d) 7.5 m
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44. Skew rays follow a _________.
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(a) Helical path through the fiber.
(b) Circular path through the fiber.
(c) Parabolic path through the fiber.
(d) Elliptical path through the fiber.
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34. ?
(a) (b)
(c) (d)
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35. _________
(a) (b)
(c) (d)
36. r
1 1 1 1
(a) (b) (c) (d)
r r2 r3 r4
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37. (....)
(a) 0 1 (b) –1 +1 (c) 0 (d) 1
38. ?
(a) (b) .. (c) (d) ..
39. “ ” ?
(a) .... (b) ....
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(c) (d)
40. RF 50 40 pF/m
(a) 10 H/m (b) 1 H/m (c) 0.1 H/m (d) 0.01 H/m
41.
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1.50 1.47
(a) 34.1 (b) 69.1 (c) 24.5 (d) 17.4
42.
50 0.2 1 m
?
(a) 396 (b) 247 (c) 212 (d) 302
43. - , 11.6 m
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2.2 ,
(a) 4.95 m (b) 3.75 m (c) 9.9 m (d) 7.5 m
44. Skew _________
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(a) (b)
(c) (d)
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45. Which optical devices are adopted or applicable for routing signals from one wave guide to
another ?
(a) Optical combiner (b) Optical coupler
(c) Optical splitter (d) None of these
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46. The maximum angle to the axis at which light may enter the fiber in order to be propagated
is known as
(a) Critical angle (b) Refractive index
(c) Numerical aperture (d) Acceptance angle
47. Name the scientific principle behind the working of optical fiber.
(a) Total external refraction of light
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(b) Total internal refraction of light
(c) Total internal reflection of light
(d) Total external reflection of light
48. Fiber cable used for ‘Fiber to Home’ installation is _________.
(a) Single mode (b) Multimode graded
(c) Multimode step (d) Multi axis
49. Which element will be 2nd from the bottom in a stack, if following operations are performed
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in the given order ?
PUSH(A), PUSH(B), PUSH(C), POP( ), POP( ), PUSH(D), PUSH(E)
(a) D (b) E (c) B (d) A
50. A silicon chip that contains ALU, a register circuit and a control unit is called _________.
(a) Microprocessor (b) Microcomputer (c) Microcontroller (d) Microsystem
51. What will be the output of the following C language code ?
main ( ) {
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int a[3] = {1, 2, 3};
printf (“%d, %d”, a[1], a[2]);
}
(a) 1, 2 (b) 1, 1 (c) 2, 2 (d) 2, 3
52. Which of the following is an example of system software ?
(a) MS PowerPoint (b) Adobe Reader
(c) MS Word (d) None of these
53. PEC_Set-A
A process through which there is direct transfer of data between main memory and
Input/Output device without the intervention of CPU is called _________.
(a) Direct Memory Retrieval (DMR) PEC_Set-A
(b) Data Switching
(c) Direct Memory Access (DMA)
(d) Direct Access
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45.
?
(a) (b) (c) (d)
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46. , _____
(a) (b) (c) (d)
47.
(a) (b)
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(c) (d)
48. ‘ ’ _________
(a) (b) (c) (d)
49. ?
(A), (B), (C), ( ), ( ), (D), (E)
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(a) D (b) E (c) B (d) A
50. ..., _________
(a) (b) (c) (d)
51. C ?
main ( ) {
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int a[3] = {1, 2, 3};
printf (“%d, %d”, a[1], a[2]);
}
(a) 1, 2 (b) 1, 1 (c) 2, 2 (d) 2, 3
52. ?
(a) (b) (c) (d)
53. PEC_Set-A
... , /
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- , _________
(a) ( ) (b)
(c) ( ) (d) ()
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54. Following program written on RISC processor computes _________.
LOAD R1, A
LOAD R2, B
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LOAD R3, C
MUL, R1, R1, R2
STORE X, R1
(a) X = (A + B) C (b) X = (A + B)
(c) X = (A A B) (d) X = (A B)
55. Which of the following represents the correct syntax of writing comments in Python programs ?
(a) /*write comments*/ (b) #write comments
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(c) //write comments (d) /write comments/
56. Telnet command in UNIX is used to _________.
(a) transfer files between different machines.
(b) change permission of files.
(c) connect with a remote machine.
(d) change ownership of a file.
57. Which of the following is not a type of Linux operating system ?
(a) Sun system (b) Red Hat Enterprise (c) Fedora (d) Ubuntu
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58. Total number of distinct characters that are represented using ASCII code are _________.
(a) 256 (b) 138 (c) 128 (d) 512
59. Op code of an instruction represents _________.
(a) addressing mode of the instruction.
(b) operation of the instruction.
(c) data address of the instruction.
(d) memory address of the instruction.
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60. Which of the following is a property of RST-7.5 interrupt ?
(a) It is non-maskable interrupt. (b) It has 3 rd highest priority.
(c) It uses level-triggered signal. (d) Its vectored address is OO3CH.
61. A variant of linked list in which none of the node contains NULL pointer is known as ______.
(a) Singly linked list (b) Doubly linked list
(c) Circular linked list (d) Threaded linked list
62. Write parity bits for the following 3 bits message codes, if even parity generator is used :
(011–), (111–)
(a) 0, 0 (b) 0, 1 PEC_Set-A
(c) 1, 0 (d) 1, 1
63. Virtual inheritance is used in C++ programming to _________.
(a) avoid single inheritance. PEC_Set-A
(b) avoid multiple copies of base class data members to be inherited into derived class.
(c) expand multiple inheritance.
(d) ensure that private base class members can be accessed anywhere.
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54. RISC _________
LOAD R1, A
LOAD R2, B
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LOAD R3, C
MUL, R1, R1, R2
STORE X, R1
(a) X = (A + B) C (b) X = (A + B) (c) X = (A A B) (d) X = (A B)
55. () ?
(a) /* */ (b) #
(c) // (d) / /
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56. _________
(a) (b)
(c) (d)
57. ?
(a) (b) (c) (d)
58. ASCII ;_________
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(a) 256 (b) 138 (c) 128 (d) 512
59. _________
(a) (b)
(c) (d)
60. RST-7.5 ?
(a) - (b)
(c) - (d) OO3CH
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61. (NULL) , ___
(a) () (b) () ()
(c) () () (d) ()
62. , 3 ()
:
(011–), (111–)
(a) 0, 0 (b) 0, 1 (c) 1, 0 (d) 1, 1
63. PEC_Set-A
C++ () _________
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(a)
(b)
(c)
(d) ()
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64. Zener breakdown occurs through
(a) Avalanche effect (b) Electron-electron collision
(c) Impact ionization (d) All of the above
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65. The purpose of biasing a BJT is
(a) to set the operating point. (b) to enhance frequency response.
(c) to increase input impedance. (d) None of the above
66. Choose the correct relationship in respect of intrinsic semiconductors.
Eg Eg2
(b) n i = NC NV exp –
2 2
(a) n i = NC NV exp
KT KT
Eg Eg
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2 2
(c) n i = NC NV exp – (d) n i = NC NV exp –
2KT KT
67. A thyristor can be used as
(a) a resistor (b) a switch (c) an amplifier (d) a power source
68. When the drain current is less than IDSS, a JFET acts like a
(a) Current source (b) Resistor (c) BJT (d) Voltage source
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69. For how many degrees of input signal does a Class-C power amplifier conduct ?
(a) 360 degrees (b) 270 degrees
(c) 180 degrees (d) Less than 180 degrees
70. The maximum conversion efficiency of a Class-B Push Pull amplifier is
(a) 66.6% (b) 70.7% (c) 78.5% (d) 91.5%
71. When the ac base voltage is too large in a bipolar transistor, the ac emitter current is
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(a) sinusoidal (b) constant (c) distorted (d) alternating
72. At low frequencies, the coupling capacitors produce a decrease in _________ in an amplifier.
(a) input resistance (b) voltage gain
(c) generator resistance (d) generator voltage
73. Which doping technique is used near room temperature ?
(a) Ion implantation (b) Diffusion
(c) Crystal growth (d) All of the above
74. PEC_Set-A
It is not possible to fabricate _________ in a monolithic IC.
(a) a diode (b) an inductor (c) a capacitor (d) a resistor
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75. The advantage of VLSI is
(a) High speed switching only (b) Cost reduction only
(c) Miniaturization only (d) All of the above
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64.
(a) (b) -
(c) (d)
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65. BJT
(a) (b)
(c) (d)
66.
Eg Eg2
n i = NC NV exp –
2 2
(a) n i = NC NV exp (b)
KT KT
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2 Eg 2 Eg
(c) n i = NC NV exp – (d) n i = NC NV exp –
2KT KT
67. ______
(a) (b) (c) (d)
68. IDSS JFET ?
(a) (b) (c) BJT (d)
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69. -C ?
(a) 360 (b) 270 (c) 180 (d) 180
70. -B - ?
(a) 66.6% (b) 70.7% (c) 78.5% (d) 91.5%
71. .. .. ?
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(a) (b) (c) (d)
72. _________
(a) (b) (c) (d)
73. ?
(a) (b) (c) (d)
IC _________
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74.
(a) (b) (c) (d)
75. VLSI PEC_Set-A
(a) (b)
(c) (d)
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SECTION – B
76. In the circuit shown in the figure, the current response, i(t) is
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t
V RC V
(a) e (b) (t)
R R
t 1
V 1 RC V
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RC
(c) δ(t) e (d) δ(t) e
R RC R
77. The voltage transfer function of the network shown in the figure is
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1 1
(a) (b) 1 + 4S (c) (d) 6 – S
1 + 2S 1 + 2S2
78. A network is said to be linear if and only if
(a) the response is proportional to the excitation function.
(b) the principle of superposition applies.
(c) the principle of homogeneity applies.
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(d) both the principles of homogeneity and superposition apply.
79. Hybrid parameters in terms of Y-parameters are given by
1 Y12 Y21 Y
(a) h11 = , h12 = , h21 = ,h =
Y12 Y11 Y11 22 Y12
1 Y12 Y21 Y
(b) h11 = , h12 = – , h21 = ,h =
Y11 Y11 Y11 22 Y11
1 Y12 Y11 Y11
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(c) h11 = , h12 = , h21 = , h22 =
Y11 Y11 Y21 Y
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(d) None of the above
80. The Routh-Hurwitz criterion gives information about
(a) the relative stability (b) % stability
(c) the absolute stability (d) None of the above
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-
76. i(t) ?
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t
V RC V
(a) e (b) (t)
R R
t 1
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V 1 RC V
RC
(c) δ(t) e (d) δ(t) e
R RC R
77. ________
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1 1
(a) (b) 1 + 4S (c) (d) 6 – S
1 + 2S 1 + 2S2
78.
(a)
(b)
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(c)
(d)
79. Y- :
1 Y12 Y21 Y
(a) h11 = , h12 = , h21 = , h22 =
Y12 Y11 Y11 Y12
1 Y12 Y21 Y
(b) h11 = , h12 = – , h21 = , h22 =
Y11 Y11 Y11 Y11
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1 Y12 Y11 Y11
(c) h11 = , h12 = , h21 = , h22 =
Y11 Y11 Y21 Y
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(d)
80. - ?
(a) (b) %
(c) (d)
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4S2 + 3S + 2
81. A voltage having the laplace transform is applied across a 2 H inductor having
7S2 + 6S + 5
zero initial current. What is the current in the inductor at t = ?
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1 2 2
(a) 0 A (b) A (c) A (d) A
5 7 5
82. The source that can emit a plane wave
(a) A plane source (b) A point source (c) A linear source (d) None of these
83. A Vector field V is called irrotational if
2
(a) V = 0 (b) V = 0 (c) V = 0 (d) None of these
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84. The electric field inside a conductor will be
(a) 0 (b)
(c) equal to electric field at the surface (d) None of these
85. The Gauss law in differential form can be written as _________.
(a) D = (b) D = (c) D = 0 (d) E = 0
0
86. Which of the following is Ampere’s law ?
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B
(a) B = 0 (b) E = –
t
D
(c) E =
(d) B = 0 J +
0 t
87. A distortionless transmission line is one in which the attenuation constant is
(a) phase independent (b) phase dependent
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(c) frequency independent (d) frequency dependent
88. The most commonly used null detector in a power frequency ac bridge is a
(a) D’ Arsanval galvanometer (b) Vibration galvanometer
(c) Ballistic galvanometer (d) Techometer
89. Kelvin double bridge is best suited for the measurement of
(a) Low resistance (b) Inductance (c) Capacitance (d) High resistance
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90. A digital to analog converter with a full scale output voltage of 3.5 V has a resolution close
to 14 mV. Its bit size is
(a) 4 (b) 16 (c) 32 (d) 8
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91. The Q-meter works on the principle of _________.
(a) Mutual inductance (b) Self-inductance
(c) Series resonance (d) Parallel resonance
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Text of page 19
4S2 + 3S + 2
81. 7S2 + 6S + 5 2 H
t = ?
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1 2 2
(a) 0 A (b) A (c) A (d) A
5 7 5
82.
(a) (b) (c) (d)
83. V
2
(a) V = 0 (b) V = 0 (c) V = 0 (d)
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84.
(a) 0 (b)
(c) (d)
85. _________
(a) D = (b) D = (c) D = 0 (d) E = 0
0
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86. ?
B
(a) B = 0 (b) E = –
t
D
(c) E =
(d) B = 0 J +
0 t
87. ________
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(a) (b) (c) (d)
88. ?
(a) ’ (b)
(c) (d)
89. ?
(a) (b) (c) (d)
90. PEC_Set-A
3.5 V 14 mV
?
(a) 4 (b) 16 PEC_Set-A (c) 32 (d) 8
91. Q- _________
(a) (b) (c) (d)
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92. An aquadag is used in CRO to collect
(a) Primary electrons
(b) Secondary emission electrons
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(c) Both Primary and Secondary emission electrons
(d) None of the above
93. Which one of the following is a passive transducer ?
(a) Piezoelectric (b) Tachogenerator (c) Photovoltaic cell (d) LVDT
94. A power signal is one for which
(a) the total energy is finite. (b) the average power is finite.
(c) the average power is infinite. (d) None of these
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95. A difference equation is used to model
(a) Discrete time system (b) Continuous time system
(c) Digital system (d) None of these
96. If the impulse response of an LTI system is h(t) = e–at u(t). What is the system’s transfer
function ? Let a > 0
S 1 1 S
(a) H(S) = (b) H(S) = (c) H(S) = (d) H(S) =
S+a S–a S+a S–a
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97. If the laplace transform of a signal x(t) = X(S), what is the laplace transform of the time-
shifted signal x(t – a) ?
(a) X(S + a) (b) X(S – a) (c) e–as X(S) (d) eas X(S)
98. A random signal is a signal whose values are
(a) Deterministic (b) Probabilistic (c) Constant (d) Zero
99. If X(t) = e–t u(t) and h(t) = e–3t u(t) using convolution theorem, the value y(t) = X(t) h(t) is
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e–t + e–3t e–t – e–3t
(a) (e–t – e–3t) u(t) (b) (e–t + e–3t) u(t) (c) u(t) (d) u(t)
4 2
100. For the given waveform
The Laplace transform is
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1 e–TS e–TS 1 e–TS
(a) A 2 – – 2 (b) A 2 –
TS S TS TS S
–TS
1 e A
(c) A 2 – 2 (d)
TS TS TS
Series-A 20 PEC
Text of page 21
92. CRO ______
(a) (b)
(c) (d)
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93. ?
(a) (b) (c) (d) LVDT
94.
(a) (b)
(c) (d)
______
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95.
(a) (b)
(c) (d)
96. LTI h(t) = e–at u(t) , a > 0 ,
?
S 1 1 S
(a) H(S) = (b) H(S) = (c) H(S) = (d) H(S) =
S+a S–a S+a S–a
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97. x(t) X(S) - x(t – a)
?
(a) X(S + a) (b) X(S – a) (c) e–as X(S) (d) eas X(S)
98.
(a) (b) (c) (d)
99. X(t) = e–t u(t) h(t) = e–3t u(t) , y(t) = X(t) h(t)
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e–t + e–3t e–t – e–3t
(a) (e–t – e–3t) u(t) (b) (e–t + e–3t) u(t) (c) u(t) (d) u(t)
4 2
100. ?
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1 e–TS e–TS 1 e–TS
(a) A 2 – – 2 (b) A 2 –
TS S TS TS S
1 e–TS A
(c) A 2 – 2 (d)
TS TS TS
PEC 21 Series-A
Text of page 22
S+1 f(t) = 1, then value of K is
101. If F(S) = and t 2
S(S + K)
1
(a) (b) 1 (c) 2 (d) 0
2
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102. Microwave tubes operate in the frequency range of
(a) 1 MHz – 1 GHz (b) 300 MHz – 300 GHz
(c) 300 GHz – 300 THz (d) 300 THz – 300 PHz
103. If a Gunn diode has a drift velocity of 105 m/s and a length of 10 m, what is the frequency
of oscillation ?
(a) 40 GHz (b) 30 GHz (c) 20 GHz (d) 10 GHz
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104. Varactor diodes are used for following purposes :
(a) Frequency multiplication (b) Parametric amplification
(c) Frequency tunning (d) All of the above
105. Efficiency of IMPATT diodes is
(a) > 30% (b) < 30% (c) > 40% (d) > 50%
106. If the S11 parameter of a two-port network is –10 dB, what is the reflection co-efficient ?
(a) 0.1 (b) 0.2 (c) 0.3 (d) 0.4
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107. If the S21 parameter of a two-port network is 20 dB, what is the gain ?
(a) 400 (b) 300 (c) 100 (d) 200
108. The maximum power received by a receiver antenna is given by
2 2
(a) Pr(max) = PT GT GR (b) Pr(max) = GT GR
4 D 4 D
2
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(c) Pr(max) = PT GT (d) None of these
4 D
109. How many electron guns are there in a colour TV ?
(a) 05 (b) 04 (c) 03 (d) 02
110. A radar is operating at a frequency of 100 GHz. If the antenna diameter is 2 m, then beam
width of the antenna will be
(a) 0.205 degree (b) 0.105 degree (c) 0.305 degree (d) 0.405 degree
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111. The transducer used in the recording works for television transmission on the principle of
(a) Electromagnetic induction (b) Photoelectric effect
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(c) Roman’s effect (d) Rayleigh’s effect
112. For an isotropic antenna, free space path loss is given by
D2 D2 4 2 4 D2
(a) Lp = (b) Lp = (c) Lp = (d) Lp =
D
Series-A 22 PEC
Text of page 24
113. A TV screen has a diagonal dimensions of 50 inches and a resolution of 1920 1080 pixels.
What is the pixel pitch ?
(a) 0.37 mm (b) 0.47 mm (c) 0.57 mm (d) 0.67 mm
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114. OLED TVs use organic light emitting diodes as
(a) The pixels (b) The backlight (c) The colour filter (d) None of the above
115. A Frequency Hopping Spread Spectrum (FHSS) system is used in
(a) Jamming
(b) Counter Jamming
(c) Both Jamming & Counter Jamming
(d) None of the above
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116. The radar transmitter generates
(a) A pulsed wave (b) A continuous wave
(c) Both continuous and pulsed wave (d) None of the above
117. If a CW radar operates at a frequency of 10 GHz and has a Doppler shift of 1 KHz, what is
the target velocity ? (Assume : Speed of light = 3 108 m/s)
(a) 30 m/s (b) 45 m/s (c) 60 m/s (d) 15 m/s
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118. The capacitive susceptance is given by
(a) Bc = jC (b) Bc = j/C (c) Bc = j/C (d) Bc = –j/C
119. A two-port network is reciprocal if and only if
(a) Z11 = Z22 (b) BC – AD = –1 (c) Y12 = –Y21 (d) h12 = h21
120. The resonant frequency of a series RLC circuit is
1 1
(a) (b) 2 LC (c) LC (d)
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2 LC LC
121. The laplace transform of the unit step function u(t) is
1 1
(a) (b) 2 (c) S (d) S2
S S
122. Which of the following is not a condition for the application of the superposition theorem ?
(a) The circuit must be linear.
(b) The circuit must have only independent sources.
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(c) The circuit must have independent sources.
(d) The circuit must be bilateral.
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123. In a balanced 3-phase star connected system, the line voltage is 400 V. What is the phase
voltage ?
(a) 220 V (b) 231 V (c) 400 V (d) 110 V
Series-A 24 PEC
Text of page 25
113. .. 50 1920 1080
?
(a) 0.37 mm (b) 0.47 mm (c) 0.57 mm (d) 0.67 mm
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114. .. ?
(a) (b) (c) (d)
115. (FHSS) ?
(a) (b)
(c) (d)
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116. ?
(a) (b)
(c) (d)
117. CW 10 GHz 1 KHz
? ( : = 3 108 m/s )
(a) 30 m/s (b) 45 m/s (c) 60 m/s (d) 15 m/s
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118.
(a) Bc = jC (b) Bc = j/C (c) Bc = j/C (d) Bc = –j/C
119. - ,
(a) Z11 = Z22 (b) BC – AD = –1 (c) Y12 = –Y21 (d) h12 = h21
120. RLC
1 1
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(a) (b) 2 LC (c) LC (d)
2 LC LC
121. u(t)
1 1
(a) (b) 2 (c) S (d) S2
S S
122. ?
(a)
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(b) only
(c)
(d)
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123. 3- 400 V ?
(a) 220 V (b) 231 V (c) 400 V (d) 110 V
PEC 25 Series-A
Text of page 26
124. Two coils with self-inductance L1 = 1 H and L2 = 2 H, have a mutual inductance of = 0.5 H.
Find the co-efficient of coupling between the coils.
1 1
(a) 0.354 (b) 0.142 (c) (d)
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3.54 0.142
125. A system has multiple poles at the same point on j-axis. The system is
(a) stable (b) unstable
(c) marginally stable (d) conditionally stable
126. When tolerance is taken as 2%, the settling time of a system for damping ratio and
frequency Wn is given by _________.
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4
(a) 4 Wn (b) 4 (c) (d) Wn
Wn Wn
127. A type 1 system is subjected to acceleration input signal, then its steady state error will be
1
(a) 1 (b) K (c) (d)
K
128. The system having characteristic equation S 2 + 4S + 10 = 0, will be
(a) underdamped (b) critically damped
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(c) overdamped (d) undamped
1
129. The type and order of a system with the transfer function are respectively
S(S + 1)
(a) Type-0 and Order-1 (b) Type-2 and Order-1
(c) Type-1 and Order-2 (d) Type-1 and Order-1
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130. A second order system exhibits 100% overshoot. Its damping co-efficient is
(a) 0 (b) 1 (c) less than 1 (d) greater than 1
131. A lag network for compensation generally consists of
(a) R and C in series on the input side.
(b) R and C in series on the output side.
(c) R and L in series on the output side.
(d) R and C in parallel on the input side.
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132. If PID controller is applied for controlling a system, then it
(a) increases the steady state error and increases transient response.
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(b) makes transient response poorer and decreases steady state error.
(c) decreases steady state error and improves transient response.
(d) increases steady state error and decreases rise time.
Series-A 26 PEC
Text of page 27
124. - L1 = 1 H L2 = 2 H = 0.5 H
1 1
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(a) 0.354 (b) 0.142 (c) (d)
3.54 0.142
125. j- ,
(a) (b) (c) (d)
126. Wn , 2%
4
(a) 4 Wn (b) 4 (c) (d) Wn
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Wn Wn
127. -1 , -
1
(a) 1 (b) K (c) (d)
K
128. S2 + 4S + 10 = 0 ,
(a) (b) (c) - (d)
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1
129.
S(S + 1)
(a) -0 -1(b) -2 -1 (c) -1 -2 (d) -1 -1
130. - 100% ,
(a) 0 (b) 1 (c) 1 (d) 1
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131.
(a) R C
(b) R C
(c) R L
(d) R C
132. ...
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(a) -
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(b) -
(c) -
(d) -
PEC 27 Series-A
Text of page 28
133. A substance can be piezoelectric only if the unit cell
(a) lacks center of inversion. (b) lacks center of plane.
(c) has polarization. (d) None of these
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134. For an extrinsic semiconductor at constant temperature, the product of numbers of electrons
and holes is as below.
(a) Remains constant (b) Vary
(c) Depends on the doping (d) None of the above
135. Physical origin of superconductivity lies in the interaction between following :
(a) Photons and phonons
(b) Conduction electrons and the ions of the lattice
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(c) Conduction electrons and photons
(d) None of the above
136. The electrical resistivity () in conductors is given by
m n m m
(a) = 2 (b) = 2 (c) = (d) =
ne me ne e2
137. A high Q quartz crystal exhibits series resonance at the frequency w s and parallel resonance
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at the frequency wp, then
(a) ws is very close but greater than wp (b) ws >> wp
(c) ws << wp (d) ws is very close but lesser than wp
138. Optical material having isotropic crystal structure is as below
(a) KDP (b) LiNbO3 (c) GaAs (d) None of the above
–
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139. The Boolean expression A + AB is equivalent to _________.
(a) A (b) A + B (c) B (d) None of the above
140. A flip-flop is also known as _________.
(a) Bistable Multivibrator (b) Astable Multivibrator
(c) Monostable Multivibrator (d) Q-stable Multivibrator
141. Which of the following is known as non-saturated logic ?
(a) RTL (b) DTL (c) TTL (d) ECL
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142. A PLA is similar to a ROM in concept except that _________
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(a) it has not the capability to read only.
(b) it has not the capability to read or write operation.
(c) it does not provide full decoding to the variables.
(d) it has not the capability to write only.
Series-A 28 PEC
Text of page 29
133.
(a) (b)
(c) (d)
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134.
(a) (b)
(c) (d)
135. :
(a) (b)
(c) (d)
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136. () ?
m n m m
(a) = 2 (b) = 2 (c) = (d) =
ne me ne e2
137. Q- ws wp ,
(a) ws wp wp
(b) ws >> wp
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(c) ws << wp
(d) ws wp wp
138. :
(a) KDP (b) LiNbO3 (c) GaAs (d)
–
139. A + AB ?
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(a) A (b) A + B (c) B (d)
140. - _________
(a) (b)
(c) (d) Q-
141. ?
(a) RTL (b) DTL (c) TTL (d) ECL
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142. PLA, ROM _________
(a) (Read only)
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(b) (read or write)
(c)
(d) (write only)
PEC 29 Series-A
Text of page 30
143. If the input of T-flipflop is 100 Hz signal, the final output of the three such T-flipflops in
cascade shall be
(a) 100 Hz (b) 12.5 Hz (c) 300 Hz (d) 500 Hz
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144. In a JK flipflop, toggle means
(a) Set Q = 1 and = 0
(b) Set Q = 0 and =1
(c) No change in output
(d) Change the output to the opposite state
145. The Boolean expression for the output f of the multiplexer shown below is
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––––––––– – – – ––––––––––––
– –
(a) A B C (b) AB + BC + CA (c) A B C (d) AB + BC + CA
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146. The number of control lines for a 8 to 1 multiplexer is
(a) 2 (b) 3 (c) 4 (d) 5
147. EPROM contents can be erased by exposing it to
(a) Ultraviolet rays (b) Infrared rays
(c) Burst of microwaves (d) Intense heat radiation
148. The digital logic family which has minimum power dissipation is
(a) TTL (b) RTL (c) DTL (d) CMOS
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149. For a series RLC circuit, setting R = 0 will produce
(a) An overdamped response (b) A critically damped response
(c) An underdamped response (d) None of the above
150. The time constant of the network shown in the figure is
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PEC_Set-ARC RC
(a) 2RC (b) RC (c) (d)
4 2
_________________
Series-A 30 PEC
Text of page 31
143. -- 100 Hz , --
?
(a) 100 Hz (b) 12.5 Hz (c) 300 Hz (d) 500 Hz
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144. - ?
(a) Q = 1 = 0 (b) Q = 0 = 1
(c) (d)
145. f ?
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––––––––– – – – ––––––––––––
(a) A B C (b) AB + BC + CA (c) A B C (d) AB + BC + CA
146. 8 : 1 ?
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(a) 2 (b) 3 (c) 4 (d) 5
147. EPROM ?
(a) (b)
(c) (burst) (d)
148.
(a) (b) (c) (d)
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149. RLC R = 0 (response) ?
(a) (b)
(c) (d)
150. ________
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RC RC
(a) 2RC (b) RC (c) (d)
4 2
_________________
PEC 31 Series-A
Text of page 32
Space For Rough Work /
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Series-A 32 PEC
Text of page 1
iqfyl mik/kh{kd ¼iqfyl nwjlapkj½ ijh{kk&2024
f}rh; iz'ui= & bySDVªkWfudh ,oa lapkj vfHk;kaf=dh ¼92½
Amended Answer Key Series A
1 C 51 D 101 C
2 A 52 D 102 B
3 B 53 C 103 D
4 D 54 D 104 D
5 B 55 B 105 B
6 A 56 C 106 A
7 C 57 A 107 C
8 B 58 C 108 A
9 C 59 B 109 C
10 A 60 D 110 B
11 D 61 C 111 B
12 D 62 B 112 D
13 B 63 B 113 C
14 B 64 A 114 A
15 C 65 A 115 B
16 A 66 D 116 C
17 C 67 B 117 D
18 B 68 B 118 A
19 D 69 D 119 B
20 B 70 C 120 A
21 D 71 C 121 A
22 A 72 B 122 B
23 A 73 A 123 B
24 D 74 B 124 A
25 D 75 D 125 B
26 B 76 C 126 C
27 B 77 C 127 D
28 A 78 D 128 A
29 A 79 B 129 C
30 C 80 C 130 A
31 D 81 B 131 B
32 B 82 A 132 C
33 C 83 A 133 A
34 B 84 A 134 A
35 A 85 B 135 B
36 A 86 D 136 A
37 D 87 C 137 D
38 C 88 B 138 C
39 B 89 A 139 B
40 C 90 D 140 A
41 D 91 C 141 D
42 B 92 B 142 C
43 C 93 D 143 B
44 A 94 B 144 D
45 B 95 A 145 C
46 D 96 C 146 B
47 C 97 C 147 A
48 A 98 B 148 D
49 A 99 D 149 D
50 A 100 A 150 B
Text of page 2
iqfyl mik/kh{kd ¼iqfyl nwjlapkj½ ijh{kk&2024
f}rh; iz'ui= & bySDVªkWfudh ,oa lapkj vfHk;kaf=dh
Amended Answer Key Series B
1 D 51 B 101 C
2 D 52 D 102 A
3 B 53 A 103 C
4 B 54 A 104 B
5 A 55 B 105 B
6 A 56 D 106 D
7 C 57 B 107 C
8 D 58 A 108 A
9 B 59 C 109 B
10 C 60 B 110 C
11 A 61 C 111 D
12 A 62 A 112 A
13 A 63 D 113 B
14 D 64 D 114 A
15 C 65 C 115 A
16 B 66 B 116 B
17 C 67 C 117 B
18 D 68 A 118 C
19 B 69 C 119 B
20 C 70 B 120 C
21 A 71 D 121 D
22 B 72 B 122 A
23 D 73 D 123 C
24 C 74 A 124 A
25 A 75 B 125 B
26 A 76 A 126 C
27 A 77 A 127 A
28 D 78 A 128 A
29 D 79 B 129 B
30 C 80 D 130 A
31 B 81 C 131 D
32 B 82 B 132 C
33 C 83 A 133 B
34 A 84 D 134 A
35 C 85 C 135 D
36 B 86 B 136 C
37 D 87 D 137 A
38 C 88 B 138 D
39 B 89 A 139 C
40 B 90 C 140 B
41 D 91 C 141 A
42 A 92 B 142 D
43 D 93 D 143 D
44 B 94 A 144 B
45 B 95 B 145 B
46 D 96 B 146 C
47 C 97 D 147 D
48 C 98 D 148 B
49 B 99 B 149 C
50 A 100 A 150 C
Text of page 3
iqfyl mik/kh{kd ¼iqfyl nwjlapkj½ ijh{kk&2024
f}rh; iz'ui= & bySDVªkWfudh ,oa lapkj vfHk;kaf=dh
Amended Answer Key Series C
1 A 51 D 101 A
2 D 52 D 102 C
3 C 53 C 103 A
4 B 54 A 104 B
5 C 55 C 105 C
6 D 56 A 106 A
7 B 57 C 107 B
8 C 58 B 108 B
9 A 59 D 109 A
10 B 60 B 110 D
11 A 61 D 111 C
12 C 62 A 112 B
13 A 63 B 113 A
14 A 64 B 114 D
15 A 65 D 115 C
16 D 66 B 116 A
17 D 67 B 117 A
18 C 68 A 118 C
19 B 69 A 119 B
20 D 70 C 120 A
21 C 71 D 121 D
22 A 72 B 122 D
23 C 73 C 123 B
24 B 74 A 124 B
25 D 75 D 125 D
26 C 76 D 126 D
27 B 77 D 127 B
28 B 78 B 128 C
29 D 79 A 129 C
30 B 80 C 130 C
31 D 81 A 131 A
32 B 82 C 132 A
33 B 83 B 133 B
34 D 84 B 134 D
35 C 85 D 135 C
36 C 86 C 136 B
37 B 87 B 137 A
38 A 88 B 138 D
39 B 89 C 139 C
40 D 90 D 140 B
41 A 91 A 141 A
42 A 92 B 142 B
43 B 93 A 143 A
44 D 94 A 144 C
45 B 95 B 145 C
46 A 96 B 146 B
47 C 97 C 147 D
48 B 98 A 148 A
49 C 99 C 149 B
50 A 100 D 150 D
Text of page 4
iqfyl mik/kh{kd ¼iqfyl nwjlapkj½ ijh{kk&2024
f}rh; iz'ui= & bySDVªkWfudh ,oa lapkj vfHk;kaf=dh
Amended Answer Key Series D
1 A 51 B 101 D
2 C 52 C 102 C
3 B 53 A 103 B
4 D 54 D 104 C
5 C 55 D 105 C
6 B 56 D 106 C
7 B 57 C 107 D
8 D 58 B 108 A
9 B 59 C 109 B
10 C 60 D 110 D
11 B 61 B 111 C
12 B 62 C 112 B
13 D 63 A 113 A
14 C 64 B 114 D
15 C 65 A 115 C
16 B 66 A 116 B
17 A 67 A 117 A
18 B 68 A 118 A
19 D 69 A 119 A
20 A 70 D 120 C
21 A 71 D 121 C
22 D 72 C 122 B
23 D 73 B 123 D
24 B 74 D 124 A
25 A 75 C 125 B
26 C 76 D 126 D
27 B 77 A 127 B
28 C 78 C 128 D
29 A 79 A 129 B
30 D 80 B 130 A
31 D 81 C 131 C
32 C 82 A 132 A
33 A 83 B 133 C
34 B 84 C 134 B
35 A 85 A 135 B
36 C 86 D 136 D
37 B 87 C 137 C
38 D 88 B 138 B
39 B 89 A 139 D
40 D 90 D 140 C
41 A 91 C 141 D
42 B 92 A 142 A
43 B 93 A 143 B
44 C 94 B 144 A
45 B 95 B 145 A
46 B 96 A 146 B
47 A 97 D 147 B
48 A 98 D 148 C
49 C 99 B 149 A
50 D 100 B 150 BPage 1 of 32
Source: Uttarakhand Public Service Commission. Question paper published by Uttarakhand Public Service Commission.