EEE MCQ — Electronics & Semiconductor Devices | ৫০টি প্রশ্ন ও উত্তর
Electronics BCS EEE পরীক্ষার পাশাপাশি সকল EEE চাকরির পরীক্ষায় গুরুত্বপূর্ণ। Diode, Transistor, Op-Amp থেকে শুরু করে Digital Logic পর্যন্ত — এই পোস্টে ৫০টি MCQ দেওয়া হলো।
🔬 Semiconductor Basics
1. A semiconductor material has a resistivity in the range of:
a) 10⁻⁶ Ω·m (conductor range) b) 10⁻⁴ to 0.5 Ω·m
c) Above 10⁸ Ω·m (insulator range) d) Exactly 1 Ω·m
✅ Answer: b
2. Silicon has how many valence electrons?
a) 2 b) 3 c) 4 d) 8
✅ Answer: c
3. In an N-type semiconductor, the majority charge carriers are:
a) Holes b) Electrons c) Protons d) Neutrons
✅ Answer: b
4. In a P-type semiconductor, majority charge carriers are:
a) Electrons b) Neutrons c) Holes d) Protons
✅ Answer: c
5. Doping a semiconductor with pentavalent (5-valence) atoms creates:
a) P-type semiconductor b) Intrinsic semiconductor
c) N-type semiconductor d) Insulator
✅ Answer: c
6. Doping with trivalent (3-valence) atoms creates:
a) N-type semiconductor b) P-type semiconductor
c) Conductor d) Intrinsic semiconductor
✅ Answer: b
📡 Diode
7. A P-N junction diode conducts current mainly in:
a) Reverse bias only b) Both directions equally
c) Forward bias d) Zero bias only
✅ Answer: c
8. The barrier potential of a silicon diode is approximately:
a) 0.3V b) 0.7V c) 1.1V d) 0.1V
✅ Answer: b
9. A Zener diode is operated in:
a) Forward bias for regulation b) Reverse bias beyond breakdown for voltage regulation
c) Zero bias d) Forward bias for switching
✅ Answer: b
10. A Schottky diode differs from a regular P-N diode in that it:
a) Has higher forward voltage drop b) Is made of two P-type materials
c) Has very fast switching due to metal-semiconductor junction d) Works only at high voltage
✅ Answer: c
11. In a full-wave bridge rectifier with 4 diodes, how many diodes conduct at a time?
a) 1 b) 2 c) 3 d) 4
✅ Answer: b
12. The ripple frequency of a full-wave rectifier with 50 Hz input is:
a) 50 Hz b) 25 Hz c) 100 Hz d) 200 Hz
✅ Answer: c
13. A varactor (varicap) diode is used as:
a) A voltage-controlled capacitor b) A rectifier
c) A voltage regulator d) A switch
✅ Answer: a
🔋 Bipolar Junction Transistor (BJT)
14. In a BJT, the three terminals are:
a) Source, Gate, Drain b) Anode, Cathode, Gate
c) Emitter, Base, Collector d) Input, Output, Ground
✅ Answer: c
15. Current gain (β or hFE) of a BJT is defined as:
a) IC / IB b) IB / IC c) IE / IB d) IC / IE
✅ Answer: a
16. In a common-emitter (CE) amplifier configuration:
a) There is no voltage gain b) Current and voltage gain are both high; output is inverted
c) Input and output are in phase d) Only current gain is achieved
✅ Answer: b
17. The common-base (CB) configuration has:
a) High current gain b) Current gain less than 1; high voltage gain; no phase inversion
c) Phase inversion d) Lowest input impedance
✅ Answer: b
18. A transistor is in saturation when:
a) Both junctions are reverse biased b) Both junctions are forward biased
c) Emitter junction is forward, collector is reverse biased d) No bias is applied
✅ Answer: b
19. A transistor acts as a switch when operated in:
a) Active region only b) Saturation and cutoff regions
c) Linear region only d) Breakdown region
✅ Answer: b
🧲 Field Effect Transistors (FET & MOSFET)
20. In an N-channel JFET, the gate-source junction is:
a) Forward biased for normal operation b) Reverse biased
c) Zero biased d) Alternately biased
✅ Answer: b
21. MOSFET stands for:
a) Metal Oxide Semiconductor Field Effect Transistor b) Modulated Output Signal Field Effect Transistor
c) Metal Output Semiconductor Frequency Effect Transistor d) Multiplexed Output Signal FET
✅ Answer: a
22. The main advantage of MOSFET over BJT is:
a) Higher current capacity b) Extremely high input impedance (voltage-controlled device)
c) Lower cost d) Better noise performance
✅ Answer: b
23. An enhancement-type MOSFET requires a gate voltage to:
a) Turn off the channel b) Create (enhance) the conducting channel
c) Reverse the drain current d) Increase gate capacitance
✅ Answer: b
📟 Operational Amplifier (Op-Amp)
24. An ideal op-amp has:
a) Zero input impedance b) Infinite input impedance and zero output impedance
c) Finite gain d) Limited bandwidth
✅ Answer: b
25. The open-loop gain of a typical op-amp (e.g., 741) is approximately:
a) 1 b) 100 c) 100,000 (10⁵) or more d) 1,000,000
✅ Answer: c
26. In a virtual ground concept of an inverting amplifier, the inverting input is:
a) Actually grounded b) At approximately 0V due to feedback, but not directly grounded
c) At supply voltage d) Floating
✅ Answer: b
27. The closed-loop gain of an inverting op-amp amplifier is:
a) Rf/Ri b) −Rf/Ri c) 1 + Rf/Ri d) Ri/Rf
✅ Answer: b
28. The closed-loop gain of a non-inverting op-amp amplifier is:
a) −Rf/Ri b) Rf/Ri c) 1 + Rf/Ri d) Ri/Rf
✅ Answer: c
29. A voltage follower (buffer) op-amp circuit has a gain of:
a) 0 b) −1 c) 1 d) Infinity
✅ Answer: c
30. A Schmitt trigger is a:
a) Linear amplifier b) Comparator with hysteresis
c) Low-pass filter d) Oscillator
✅ Answer: b
🔢 Digital Electronics
31. The binary number 1011 is equal to decimal:
a) 9 b) 10 c) 11 d) 12
✅ Answer: c (8+0+2+1 = 11)
32. The hexadecimal equivalent of decimal 255 is:
a) EE b) FE c) FF d) EF
✅ Answer: c (255 = 16×15 + 15 = FF)
33. A NAND gate is called a universal gate because:
a) It is used in all computers b) Any logic function can be implemented using only NAND gates
c) It has the highest speed d) It consumes the least power
✅ Answer: b
34. De Morgan's theorem states:
a) A·B = A+B b) (A·B)' = A' + B' c) A+B = A·B d) A' = A
✅ Answer: b
35. A half adder can add:
a) Three bits b) Two bits — produces sum and carry (no carry input)
c) Four bits d) BCD numbers
✅ Answer: b
36. A full adder differs from a half adder in that it:
a) Adds only two bits b) Also accepts a carry input from previous stage
c) Subtracts numbers d) Works only in binary
✅ Answer: b
37. A multiplexer (MUX) is a combinational circuit that:
a) Converts serial to parallel b) Selects one of many input lines and routes it to the output
c) Stores data d) Performs arithmetic operations
✅ Answer: b
38. A decoder converts:
a) Analog to digital b) Binary code to one of 2ⁿ output lines
c) Digital to analog d) Parallel to serial
✅ Answer: b
39. A flip-flop is a:
a) Combinational circuit b) Sequential circuit that stores one bit
c) Arithmetic circuit d) Multiplexer type circuit
✅ Answer: b
40. A D flip-flop is used as:
a) A counter b) A data latch (stores 1 bit on clock edge)
c) An adder d) A multiplexer
✅ Answer: b
41. A JK flip-flop with J=1, K=1 at the clock edge will:
a) Set (Q=1) b) Reset (Q=0) c) Toggle d) Hold state
✅ Answer: c
42. A ripple counter is also called:
a) Synchronous counter b) Asynchronous counter
c) Up-down counter d) Decade counter
✅ Answer: b
43. A 4-bit binary counter can count from:
a) 0 to 8 b) 0 to 15 c) 0 to 16 d) 1 to 16
✅ Answer: b
44. ADC stands for:
a) Automatic Data Counter b) Analog to Digital Converter
c) Amplified Digital Circuit d) Advanced Driver Circuit
✅ Answer: b
45. DAC stands for:
a) Digital Analog Computer b) Digital to Analog Converter
c) Data Amplification Circuit d) Direct Analog Control
✅ Answer: b
📶 Communication & Modulation Basics
46. AM (Amplitude Modulation) varies the:
a) Frequency of the carrier b) Amplitude of the carrier with the message signal
c) Phase of the carrier d) Wavelength of the carrier
✅ Answer: b
47. FM (Frequency Modulation) is preferred over AM because it has:
a) Larger bandwidth requirement b) Better noise immunity
c) Simpler circuitry d) Longer range
✅ Answer: b
48. The Nyquist sampling theorem states that a signal must be sampled at:
a) Exactly the signal frequency b) At least twice the highest frequency component
c) Half the signal frequency d) 10 times the signal frequency
✅ Answer: b
49. PCM stands for:
a) Pulse Code Modulation b) Phase Coded Message
c) Pulse Current Modulation d) Phase Current Modulation
✅ Answer: a
50. A phase-locked loop (PLL) is used for:
a) Power amplification b) Frequency synthesis, demodulation, and clock recovery
c) Digital-to-analog conversion d) Power factor correction
✅ Answer: b
গুরুত্বপূর্ণ সূত্র সংক্ষেপ
| বিষয় | সূত্র / তথ্য |
|---|---|
| BJT current gain | β = IC/IB |
| Inverting amplifier gain | Av = −Rf/Ri |
| Non-inverting amplifier gain | Av = 1 + Rf/Ri |
| Zener regulation | Operates at reverse breakdown voltage |
| Nyquist theorem | fs ≥ 2 × fmax |
পরবর্তী পোস্ট: Signals & Systems / Control Systems MCQ — ৫০টি প্রশ্ন ও উত্তর
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