Are you dreaming of a prestigious career as a Sub-Assistant Engineer (SAE) or Assistant Engineer (AE) in Bangladesh’s top power sector companies like PGCB, DPDC, or DESCO? You know that the recruitment exams, especially those following the analytical BUET pattern, are the biggest hurdle to cross.
Simply reading textbooks isn’t enough. To succeed, you must master the art of solving MCQs quickly and accurately. The best way to do that is by practicing with real questions from previous exams.
That’s why we are providing you with the complete, solved MCQ paper from the 49th BCS (EEE) Preliminary Examination held in 2025. This is a goldmine of 100 questions that will give you a real feel for the exam pattern, question difficulty, and important topics.
Go through these questions to test your knowledge. But remember, practice is just one part of the puzzle. To build a rock-solid foundation and learn the tips and tricks to solve any problem, a structured preparation is essential. That’s where our Comprehensive EEE Job Preparation Course for SAE & AE comes in.
Now, let’s dive into the questions!
Here are the 100 questions with their correct answers, analyzed by our expert instructors.
1. If the load angle of a synchronous generator increases beyond 90°, the machine will –
(a) supply reactive power (b) lose synchronism (c) act as an induction motor (d) increase stability margin
Answer: (b) lose synchronism
2. Super-heating of steam in a thermal power plant is carried out to-
(a) increase turbine efficiency (b) reduce moisture content at turbine exit (c) reduce boiler efficiency (d) both a and b
Answer: (d) both a and b
3. Which renewable energy sources has the highest energy density?
(a) Solar (b) Wind (c) Geothermal (d) Biomass
Answer: (c) Geothermal
4. A system whose output depends on present and past inputs is called-
(a) linear (b) LTI (c) causal (d) stable
Answer: (c) causal
5. MOSFETS are-
(a) current controlled device (b) voltage-controlled device (c) bipolar device (d) devices with independent source
Answer: (b) voltage-controlled device
6. Which of the following is a universal gate?
(a) AND (b) OR (c) NOR (d) XOR
Answer: (c) NOR
7. In a rectifier, ripple factor is defined as-
(a) ratio of input to output voltage (b) ratio of load resistance to input resistance (c) ratio of DC to AC component (d) ratio of AC to DC component
Answer: (d) ratio of AC to DC component
8. The principle of operation of transformer is-
(a) Ohm’s Law (b) Faraday’s Law (c) Ampere’s Law (d) Lenz’s Law
Answer: (b) Faraday’s Law
9. The guard band is used in FDM to-
(a) increase channel capacity (b) reduce noise (c) improve modulation index (d) prevent interference between adjacent channels
Answer: (d) prevent interference between adjacent channels
10. In a hydroelectric power plant, the potential of energy of water is converted into-
(a) heat energy (b) electrical energy (c) kinetic energy and then to electrical energy (d) chemical energy
Answer: (c) kinetic energy and then to electrical energy
11. An SCR has how many p-n junctions?
(a) 1 (b) 2 (c) 3 (d) none of the above
Answer: (c) 3
12. Root-locus plot shows-
(a) system zeros (b) step response (c) frequency response (d) system poles with varying gains
Answer: (d) system poles with varying gains
13. PWM is used in power electronics for-
(a) reducing switching loss (b) voltage and frequency control (c) AC and DC conversion (d) energy storage
Answer: (b) voltage and frequency control
14. For an underdamped system, the response exhibits-
(a) exponential decay (b) linear rise (c) constant output (d) oscillations
Answer: (d) oscillations
15. In amplitude modulation (AM)-
(a) the amplitude of the message signal varies (b) the amplitude of the carrier signal varies (c) the frequency of the carrier signal varies (d) the phase of the message signal varies
Answer: (b) the amplitude of the carrier signal varies
16. Laplace domain representation of unit step function is-
(a) s (b) 1/S (c) S² (d) 1
Answer: (b) 1/S
17. Commutator is used in-
(a) Induction motor (b) Transformer (c) DC machines (d) Synchronous machines
Answer: (c) DC machines
18. The insulation level of transmission lines is mainly chosen from-
(a) current carrying capacity (b) power factor (c) voltage level (d) frequency
Answer: (c) voltage level
19. In a PV cell, the short circuit current, Isc depends mainly on-
(a) temperature (b) irradiance (c) series resistance (d) shunt resistance
Answer: (b) irradiance
20. A fuel cell directly converts-
(a) Chemical energy into heat (b) Chemical energy into electrical energy (c) heat into mechanical energy (d) mechanical energy into electrical energy
Answer: (b) Chemical energy into electrical energy
21. A Zener diode is used in circuits for-
(a) voltage regulation (b) rectification (c) amplification (d) Oscillation
Answer: (a) voltage regulation
22. When a synchronous generator is over-excited, and connected to an infinite bus, it acts as a-
(a) pure active power source (b) voltage regulator (c) lagging pf load (d) capacitor, supplying reactive power
Answer: (d) capacitor, supplying reactive power
23. Superposition theorem can be applied to circuits containing-
(a) Linear elements only (b) Non-linear elements only (c) Both linear and non-linear elements (d) only passive elements
Answer: (a) Linear elements only
24. The frequency at which the magnitude of open loop transfer function becomes unity is called-
(a) resonant frequency (b) natural frequency (c) phase cross-over frequency (d) gains cross-over frequency
Answer: (d) gains cross-over frequency
25. In a Rankine Cycle, the ideal location for reheating steam is-
(a) between turbine stages (b) before entering the condenser (c) at boiler inlet (d) before feed pump
Answer: (a) between turbine stages
26. Which modulation technique is generally used in optical fiber communication?
(a) OOK (b) PSK (c) QPSK (d) FSK
Answer: (a) OOK (On-Off Keying)
27. In an FM system, if modulation index exceeds 1, the system experiences-
(a) under modulation (b) over modulation and disruption (c) linear amplification (d) change in waveform
Answer: (b) over modulation and disruption
28. For an ideal Op-Amp-
(a) CMRR=∞ (b) Bandwidth=0 (c) Slew rate=0 (d) Input off set voltage>0
Answer: (a) CMRR=∞
29. The settling time of a second order under-damped system is inversely proportional to-
(a) damping ratio (b) natural frequency (c) gain (d) both a and b
Answer: (d) both a and b
30. Fading caused by rapid multi-path changes due to mobility is called-
(a) Flat fading (b) Fast fading (c) selective fading (d) shadow fading
Answer: (b) Fast fading
31. The function of an economizer in a steam power plant is to-
(a) increase steam temperature (b) reheat steam (c) preheat feed water (d) reduce exhaust gases
Answer: (c) preheat feed water
32. In an induction machine, maximum torque is produced when-
(a) Slip = 1 (b) rotor resistance = rotor reactance (c) high rotor resistance (d) operates at unity pf
Answer: (b) rotor resistance = rotor reactance
33. Nyquist sampling theorem states that the sampling frequency must be at least-
(a) equal to signal frequency (b) twice the maximum signal frequency (c) half the maximum signal frequency (d) four times the signal frequency
Answer: (b) twice the maximum signal frequency
34. The root locus technique is used to study-
(a) time response (b) frequency response (c) system stability with gain variation (d) error dynamics
Answer: (c) system stability with gain variation
35. A cyclo-converter converts-
(a) DC-DC (Voltage) (b) AC-AC (frequency) (c) DC-AC (Voltage) (d) AC-DC (Voltage)
Answer: (b) AC-AC (frequency)
36. The time constant of an RL circuit is given by-
(a) R+L (b) R*L (c) L/R (d) 1/LR
Answer: (c) L/R
37. The current drawn by the input terminals of an ideal Op-Amp is-
(a) infinite (b) Zero (c) equal to output current (d) none of the above
Answer: (b) Zero
38. A single-phase transformer is said to have maximum efficiency when-
(a) Core loss = copper loss (b) core loss > copper loss (c) core loss < copper loss (d) none of the above
Answer: (a) Core loss = copper loss
39. Which of the following modulation is most bandwidth-efficient?
(a) FSK (b) BPSK (c) QPSK (d) 16-QAM
Answer: (d) 16-QAM
40. A single-phase induction motor is not self-starting because-
(a) no net starting torque is produced (b) rotor has no field (c) high rotor resistance (d) it operates at unity power factor
Answer: (a) no net starting torque is produced
41. In sinusoidal steady state, which analysis is commonly used-
(a) Laplace (b) Phasor (c) Fourier (d) Transient
Answer: (b) Phasor
42. Which nuclear fuel is most commonly used in nuclear reactors?
(a) Thorium-232 (b) Plutonium-239 (c) Uranium-235 (d) Carbon-14
Answer: (c) Uranium-235
43. The main reason for using a bypass capacitor connected across the emitter resistance in a CE amplifier is to-
(a) increase input impedance (b) reduce AC gain (c) Stabilize DC operating point (d) increase AC gain without affecting DC bias
Answer: (d) increase AC gain without affecting DC bias
44. In a forward-biased PN junction diode, the barrier potential-
(a) decreases (b) becomes negative (c) remains constant (d) increases
Answer: (a) decreases
45. The maximum memory addressable by 8085-
(a) 64 KB (b) 32 KB (c) 16 KB (d) 128 KB
Answer: (a) 64 KB
46. Corona loss is reduced by-
(a) decreasing conductor size (b) using bundled conductor (c) increasing line voltage (d) increasing frequency
Answer: (b) using bundled conductor
47. The major cause of a boiler tube failure is-
(a) Overheating (b) Corrosion (c) Stress rupture (d) all of the above
Answer: (d) all of the above
48. An 8-bit synchronous counter counts up from 0 to 255. Total number of states is-
(a) 255 (b) 128 (c) 256 (d) none of the above
Answer: (c) 256
49. Maximum power transfer theorem is applicable only for-
(a) DC circuits (b) AC circuits (c) in both a and b (d) None of the above
Answer: (c) in both a and b
50. In a wind turbine power available in the wind is proportional to-
(a) wind speed (b) Square of the wind speed (c) Cube of the wind speed (d) fourth power of wind speed
Answer: (c) Cube of the wind speed
51. Which instruction is used to call a subroutine in 8085?
(a) JMP (b) CALL (c) RET (d) PUSH
Answer: (b) CALL
52. The frequency at which gain drops by 3d is called-
(a) cut off frequency (b) centre frequency (c) transition frequency (d) bandwidth
Answer: (a) cut off frequency
53. BCD code of 15 is-
(a) 1111 (b) 00100101 (c) 00010101 (d) none of the above
Answer: (c) 00010101
54. In a three phase synchronous motor, the slip at synchronous speed is-
(a) Zero (b) 1 (c) between 0 and 1 (d) infinity
Answer: (a) Zero
55. In an RLC parallel circuit at resonance-
(a) the impedance is maximum and the current through the source is maximum
(b) the impedance is maximum and the current through the source is minimum
(c) the impedance is minimum and the current through the source is maximum
(d) the impedance is minimum and the current through the source is minimum
Answer: (b) the impedance is maximum and the current through the source is minimum
56. The main advantage of IGBT over MOSFET is-
(a) higher switching speed (b) lower conduction losses (c) purely resistive behaviour (d) no gate drive required
Answer: (b) lower conduction losses
57. Which IC is commonly used for interfacing a keyboard and display with 8085?
(a) 8255 (b) 8251 (c) 8259 (d) 8086
Answer: (a) 8255
58. In active region a BJT has-
(a) forward biased emitter-base and collector-bias junctions
(b) forward biased collector-base and reverse bias emitter-base junctions
(c) forward biased emitter-base and reverse-biased collector-bias junctions
(d) reverse biased emitter-base and collector-bias junctions
Answer: (c) forward biased emitter-base and reverse-biased collector-bias junctions
59. Which system will go to steady state faster?
(a) T=1.0 (b) T=0.5 (c) T=1.5 (d) T=2.0
Answer: (b) T=0.5 (A smaller time constant T means the system settles faster).
60. Which is a passive network element?
(a) voltage source (b) dependent current source (c) amplifier (d) resistance
Answer: (d) resistance
61. What is the highest distribution voltage in Bangladesh?
(a) 11 kV (b) 33 kV (c) 400V (d) 400KV
Answer: (b) 33 kV
62. The firing angle in an SCR controls-
(a) input AC frequency (b) cutout voltage and current (c) resistance of load (d) temperature of SIR
Answer: (b) cutout voltage and current
63. In a 4 bit full adder, how many output bits are there?
(a) 4 (b) 5 (c) 3 (d) 1
Answer: (b) 5 (4 sum bits and 1 carry-out bit).
64. A 1: 16 demultiplexer requires how many input Fines?
(a) 4 (b) 3 (c) 5 (d) 1
Answer: (d) 1
65. Shannon’s theorem gives-
(a) channel power (b) antenna gain (c) noise floor (d) maximum transmission rate
Answer: (d) maximum transmission rate
66. Which of the following is a serial input/output port K used with 8085?
(a) 8251 (b) 8253 (c) 8255 (d) 8254
Answer: (a) 8251
67. Impedance in the S domain for an inductor is-
(a) SL (b) 1/SL (c) S²L (d) 1/ S²L
Answer: (a) SL
68. Thermal power generation depends on-
(a) temperature difference between sea layers (b) kinetic energy of wind over sea (c) ocean salinity gradient (d) periodic salinity gradient
Answer: (a) temperature difference between sea layers (This refers to OTEC, a type of thermal generation).
69. In a nuclear power plant, the moderator is used to-
(a) absorb neutrons (b) slow down fast neutrons (c) increase reactor temperature (d) control fission rate directly
Answer: (b) slow down fast neutrons
70. The stack of a microprocessor is usually implemented in-
(a) ROM (b) RAM (c) Cache (d) Register file
Answer: (b) RAM
71. Which of the amplifiers has 180° phase shift between input to output voltages?
(a) common emitter (b) common base (c) common collector (d) emitter follower
Answer: (a) common emitter
72. Regenerative braking in a DC motor occurs when-
(a) back emf < supply voltage (b) load torque=0 (c) back emf > supply voltage (d) armature current =0
Answer: (c) back emf > supply voltage
73. The instruction cycle of a microprocessor consists of-
(a) fetch and execute cycles (b) decode and execute cycle (c) only fetch cycle (d) only execute cycle
Answer: (a) fetch and execute cycles
74. Norton’s theorem simplifies a network by representing it as-
(a) A voltage source in series with a resistance (b) A current source in series with a resistance (c) A current source in parallel with a resistance (d) A voltage source in parallel with an impedance
Answer: (c) A current source in parallel with a resistance
75. The capacity of a thermal power plant is generally measured in-
(a) Joule (b) MVA (c) BTU (d) MW
Answer: (d) MW
76. If the load of a transformer is changed, what will happen?
(a) core loss changes (b) copper loss changes (c) no load current changes (d) magnetizing current changes
Answer: (b) copper loss changes
77. In satellite communication, the most commonly used technique is-
(a) CDMA (b) TDMA (c) FDMA (d) combination of b and c
Answer: (d) combination of b and c (Both TDMA and FDMA are widely used).
78. If the voltage across a capacitor is constant, the current through it is-
(a) Zero (b) Maximum (c) infinite (d) Can not be determined
Answer: (a) Zero
79. A three-phase fault in a power system is-
(a) least common fault (b) least severe Fault (c) most sever fault (d) both a and b
Answer: (c) most sever fault
80. HVDC transmission is preferred over HVAC system for-
(a) short distances (b) long distance bulk power (c) rural distribution (d) step-down substations
Answer: (b) long distance bulk power
81. The difference between memory-mapped I/O and isolated I/O is-
(a) data width (b) address space (c) dock frequency (d) instruction set
Answer: (d) instruction set
82. The quality factor Qin a high-resonant circuit implies-
(a) High bandwidth (b) low selectivity (c) Narrow bandwidth (d) No resonance
Answer: (c) Narrow bandwidth
83. 0 dBW is equal to-
(a) dMW (b) 1 MW (c) 0.5 W (d) 1 W
Answer: (d) 1 W
84. In a combined cycle power plant, the main advantage is-
(a) lower capital cost (b) smaller footprint than wind plant (c) independent operation of each unit (d) higher overall efficiency by using both gas and steam turbines
Answer: (d) higher overall efficiency by using both gas and steam turbines
85. The speed of rotating flux of a 8-pole, 50 Hz machine is
(a) 750rpm (b) 1000 rpm (c) 1500 rpm (d) 3000 rpm
Answer: (a) 750rpm (Ns = 120f/P = 120*50/8 = 750)
86. In a D flip-flop, the output changes state-
(a) when D=0 (b) When D=1 (c) When Clock =1 (d) at clock edge
Answer: (d) at clock edge
87. In an RLC series circuit, the resonant frequency is-
(a) 1/ √(LC) (b) 1/(2π√LC) (c) 1/2π(√LCH) (d) 1/LC
Answer: (b) 1/(2π√LC)
88. The skin effect in a conductor-
(a) increases resistance at high frequency (b) decreases resistance at high frequency (c) eliminate corona loss (d) occurs only at low frequency
Answer: (a) increases resistance at high frequency
89. A steady state error for a type 1 system with a step input is-
(a) Zero (b) Finite (c) infinite (d) depends on gain
Answer: (a) Zero
90. The primary pollutant from coal fired power plant is-
(a) carbon dioxide (b) methane (c) zinc (d) Sulphur dioxide
Answer: (d) Sulphur dioxide
91. A control system that uses feedback to compare output with reference input is called-
(a) open-loop system (b) close-loop system (c) feed forward system (d) adaptive system
Answer: (b) close-loop system
92. A program counter (PC) in a microprocessor-
(a) stores the last instruction executed (b) stores the address of the last instruction executed (c) stores the address of the next instruction (d) control I/O device
Answer: (c) stores the address of the next instruction
93. In a differential amplifier, common mode gain is ideally-
(a) Zero (b) Unity (c) Infinite (d) equal to differential gain
Answer: (a) Zero
94. Corona discharge is more prominent in-
(a) low voltage, short lines (b) high voltage, long lines (c) underground cables (d) insulated transmission lines
Answer: (b) high voltage, long lines
95. The main reason for using laminated cores in machine is to-
(a) reduce hysteresis loss (b) reduce copper loss (c) reduce eddy current loss (d) increase efficiency
Answer: (c) reduce eddy current loss
96. In nuclear reactors, control rods are made of-
(a) Uranium (b) Plutonium (c) Graphite (d) Cadmium or Boron
Answer: (d) Cadmium or Boron
97. The maximum number of devices that can be connected in memory mapped I/O depends on-
(a) number of data lines (b) number of address lines (c) clock frequency (d) instruction set
Answer: (b) number of address lines
98. The output of a full wave rectifier is-
(a) pure AC (b) constant DC (c) pulsating DC (d) Sine wave
Answer: (c) pulsating DC
99. In a DC motor, if the armature current and suddenly interrupted while the meeting is running, what happens?
(a) Torque increases (b) A large back emf may damage components (c) Field current increases (d) instantly speed drops to zero
Answer: (b) A large back emf may damage components
100. In a purely capacitive AC circuit, the current
(a) leads the voltage (b) lags the voltage (c) is in phase with the voltage (d) is zero
Answer: (a) leads the voltage
Congratulations on completing the 100-question challenge! How many were you able to solve correctly and confidently?
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