Bangladesh Rural Electrification Board – Assistant Engineer (Electrical) MCQ 2014

Bangladesh Rural Electrification Board

Post: Assistant Engineer (Electrical)

Full Marks: 80 Time: 1 Hour Date: 26 September 2014

Section A — Electrical & Electronics (Q. 1–66)

• 1. Reciprocity theorem is applicable for:
  (a) Unilateral network (b) Bilateral network (c) Ideal network (d) None of the these
• 2. A JFET is also called:
  (a) Unipolar transistor (b) Bipolar transistor (c) Unijunction transistor (d) None of the these
• 3. Form Factor of sinusoidal alternating current is:
  (a) 1.11% (b) 1.11A (c) 1.11 (d) b and c
• 4. Relation between resonant power P₀ and off-resonant power P is:
  (a) P₀ = P (b) P₀ > P (c) P₀ < P (d) None of the these
• 5. In a parallel resonance ac circuit following points to be remembered:
  (a) The admittance equals conductance (b) Both a and c (c) The power factor of the circuit is unity (d) None of the above
• 6. A network which attenuates a single band of frequencies and allows those on either side to pass through is called:
  (a) Low-pass filter (b) High-pass filter (c) Bandstop filter (d) Bandpass filter
• 7. The frequency corresponding to half-power point on the response curve of a filter is known as:
  (a) cutoff (b) upper (c) lower (d) roll-off
• 8. If D is the electric flux density, then value of electric intensity of a medium is:
  (a) D/ε₀ (b) D/ε₀εᵣ (c) ε₀εᵣ/D (d) ε₀/D
• 9. The stabilization of operating point in potential divider method is provided by:
  (a) Rₑ consideration (b) R꜀ consideration (c) V꜀꜀ consideration (d) None of the these
• 10. In a differential amplifier, the CMRR is limited mostly by the:
  (a) CMMR of the op amp (b) Gain-Bandwidth product (c) Supply voltage (d) Tolerance of the resistors
• 11. Emitter follower is used for:
  (a) Current gain (b) Impedance matching (c) Voltage gain (d) None of the these
• 12. An oscillator differs from an amplifier because it:
  (a) Has more gain (b) Requires no input signal (c) Requires no dc supply (d) Always has the same input
• 13. The dimensions of L/CR are that of:
  (a) Farad (b) Henry (c) Ohm (d) None of the these
• 14. In the breakdown region, a Zener diode behaves like a:
  (a) Constant current source (b) Constant resistance (c) Forward biased (d) Constant voltage source
• 15. The maximum efficiency of a half-wave diode rectifier is:
  (a) 50% (b) 25% (c) 40.6% (d) 81.2%
• 16. The collector of a transistor is:
  (a) Heavily doped (b) Moderately doped (c) Lightly doped (d) None of the these
• 17. Transistor biasing is done to keep:
  (a) Proper ac current in the circuit (b) The base current small in the circuit (c) Proper dc current in the circuit (d) Collector current small in the circuit
• 18. According to Faraday's Laws of Electromagnetic Induction, an emf is induced in a conductor whenever it:
  (a) Lies in a magnetic field (b) Cuts magnetic flux (c) Moves parallel to the direction of the magnetic field (d) Lies perpendicular to the magnetic flux
• 19. The phase difference between the output and input voltages of a CE amplifier is:
  (a) 0° (b) 90° (c) 180° (d) 270°
• 20. If a three-stage amplifier has individual stage gains of 10 dB, 5 dB and 15 dB, then the total gain in dB is:
  (a) 750 dB (b) 30 dB (c) 25 dB (d) 7.5 dB
• 21. A push-pull circuit must use in:
  (a) Class A operation (b) Class C operation (c) Class B operation (d) Class AB operation
• 22. When transistor is used as an amplifier, it is operated in the:
  (a) Cut off region (b) Saturation region (c) Active region (d) Both a and b
• 23. For a given line voltage, four heating coils will produce maximum heat when connected in:
  (a) All in parallel (b) Two parallel pairs in series (c) All in series (d) One pair in parallel with other two in series
• 24. An SCR is turned off when:
  (a) Anode current is reduced to zero (b) Gate is reverse biased (c) Gate voltage is reduced to zero (d) All of these
• 25. A MOSFET is operated with:
  (a) Negative gate voltage only (b) Positive gate voltage only (c) Positive as well as negative gate voltage (d) None of the these
• 26. Negative feedback is employed in:
  (a) Oscillators (b) Rectifiers (c) Amplifiers (d) None of the these
• 27. In a LC oscillator, the frequency of oscillation is:
  (a) Proportional to LC (b) Proportional to square root of LC (c) Inversely proportional to the square root of LC (d) Independent of the value of LC
• 28. If dc supply of 10V is fed to a differentiating circuit, then output will be:
  (a) 20 V (b) 10 V (c) 0 V (d) a or b
• 29. The best way to minimize the eddy current in an armature:
  (a) Commutation (b) Lamination (c) Lap winding (d) All of the these
• 30. In TV transmission the voice signal is:
  (a) AM modulated (b) FM modulated (c) PM modulated (d) FSK modulated
• 31. When the modulating signal controls the frequency of the carrier we get:
  (a) Phase modulation (b) Amplitude modulation (c) Frequency modulation (d) Digital modulation
• 32. An ideal regulated power supply is one which has voltage regulation of:
  (a) 0% (b) 1.5% (c) 5% (d) 10%
• 33. If length of the cable of transmission line is doubled, its capacitance is:
  (a) Doubled (b) Halved (c) Quadrupled (d) None of the these
  Note: Capacitance is directly proportional to length, so doubling length doubles capacitance.
• 34. If a power supply has no-load and full-load voltages of 30 V and 25 V respectively, then the percentage voltage regulation is:
  (a) 10% (b) 15% (c) 20% (d) 25%
  Note: % VR = (V_NL − V_FL) / V_FL × 100 = (30 − 25) / 25 × 100 = 20%
• 35. An unbalanced system of 3-phase voltages having RYB sequence actually consists of:
  (a) A positive sequence component (b) A zero sequence component (c) A negative sequence component (d) All of the above
• 36. Zener diode can be used as:
  (a) Dc voltage regulator only (b) Ac voltage regulator only (c) Both ac and dc voltage regulator (d) None of the above
• 37. If supply frequency is increased then skin effect is:
  (a) Increase (b) Decrease (c) No change (d) None of the these
• 38. Voltage control method of ac power system is:
  (a) By excitation control (b) Auto transformer tap changing (c) By synchronous condenser (d) All of the these
• 39. Most accurate device for measuring voltage is:
  (a) Voltmeter (b) Multimeter (c) CRO (d) Both a and b
• 40. Primary winding of CT is connected:
  (a) In series with the load (b) In parallel with the load (c) Between line and neutral (d) Both a and b
• 41. A galvanometer in series with high resistance is called:
  (a) An ammeter (b) A voltmeter (c) An wattmeter (d) None of the these
• 42. Calibration voltage for an oscillator is:
  (a) 2 V Peak to peak (b) 2 V RMS voltage (c) 2 V average voltage (d) 2 V sinusoidal voltage
• 43. The universal gate is:
  (a) AND gate (b) OR gate (c) NAND gate (d) NOR gate
  Note: Both NAND and NOR are universal gates; NAND is the primary standard answer.
• 44. The speed of dc motor can be controlled by varying:
  (a) Its flux per pole (b) Resistance of armature circuit (c) Applied voltage (d) All of the these
• 45. The most likely causes of sparking at the brushes in a dc machine is/are:
  (a) Open coil in the armature (b) Defective interpoles (c) Incorrect brush spring pressure (d) All of these
• 46. Which of the following machines may be used as power factor correction?
  (a) Induction motor (b) Synchronous motor (c) Alternator (d) All of the these
• 47. If residual magnetism of a shunt generator is destroyed accidentally, it may be restored by connecting its shunt field:
  (a) To an ac source (b) To earth (c) In reverse (d) To a dc source
• 48. An integrating circuit is a simple RC series circuit with output taken across:
  (a) R (b) C (c) Both R and C (d) Any of R and C
• 49. Which of the following quantity maintains the same direction whether a dc machine runs as a generator or as a motor?
  (a) Induced emf (b) Armature current (c) Field current (d) Supply current
• 50. The sole purpose of commutator in a dc Generator is to:
  (a) Increase output voltage (b) Reduce sparking at brushes (c) Provide smoother output (d) Convert the induced ac into dc
• 51. The power factor of an alternator is determined by its:
  (a) Speed (b) Load (c) Excitation (d) Prime mover
• 52. A transformer transforms:
  (a) Frequency (b) Voltage (c) Current (d) Voltage and current
• 53. When speed of an alternator is changed from 3600 rpm to 1800 rpm the generated emf/phase will become:
  (a) One-half (b) Twice (c) Four times (d) One-fourth
• 54. A dc motor fails to start when switched on due to following causes:
  (a) Low terminal voltage (b) Overload (c) Excessive friction (d) All of these
• 55. The direction of force on a current carrying conductor placed in a magnetic field may be found by Fleming's Right hand rule.
  (a) True (b) False (c) None of these
  Note: Fleming's Left Hand Rule (Motor rule) applies here, not the Right Hand Rule.
• 56. If the spacing between the conductors of transmission line is increased the corona effect is also increased.
  (a) True (b) False
  Note: Increased conductor spacing raises the critical disruptive voltage, thereby reducing corona effect.
• 57. Excessive sparking at the brushes is one of the indications of overloading of a generator.
  (a) True (b) False
• 58. A distribution transformer links the primary and secondary distribution system.
  (a) False (b) True
• 59. A Squirrel cage induction motor runs at a constant speed only so long as:
  (a) Its supply voltage remains constant (b) Its torque exactly equals the mechanical load (c) Stator flux remains constant (d) Torque develop by it remains constant
• 60. The direction of rotation of a single-phase induction motor can be reversed by:
  (a) Reversing connections of both windings (b) Reversing connections of starting winding (c) Using a reversing switch (d) Reversing supply connections
• 61. There is no transient in a pure resistive circuit.
  (a) False (b) True (c) None of these
• 62. Over modulation occurs when signal amplitude greater than the carrier amplitude.
  (a) True (b) False
• 63. In a three phase induction motor, the relative speed of stator flux and rotor flux is called slip.
  (a) False (b) True
• 64. Speed of dc motor is directly proportional to the flux Φ and inversely proportional to the back emf Eᵦ.
  (a) True (b) False
  Note: N ∝ Eᵦ / Φ — speed is directly proportional to back emf and inversely proportional to flux.
• 65. The correct antonym of the word 'benign' is ________
  (a) malignant (b) peaceful (c) blessed (d) ten fold
• 66. Choose the correct one —
  (a) maintainance (b) bureocracy (c) burocracy (d) bureaucracy

Section B — Bangla & General Knowledge (Q. 67–80)

• ৬৭. শুদ্ধ বানান কোনটি?
  ক) মুমূর্ষ খ) মুমুর্ষ গ) মুমূর্ষ ঘ) মুমূর্ষু
• ৬৮. 'সকালে উঠিয়া আমি মনে মনে বলি' — রচয়িতা কে?
  ক) কৃষ্ণচন্দ্র মজুমদার খ) যতীন্দ্রমোহন বাগচী গ) কুসুমকুমারী দাস ঘ) রবীন্দ্রনাথ ঠাকুর
• ৬৯. রেনেসাঁ হলো —
  ক) একটি ভাস্কর্যের নাম খ) কোনটিই নয় গ) একজন শিল্পীর নাম ঘ) বিশেষ আন্দোলনের নাম
• ৭০. এক নটিক্যাল মাইলে কত কিলোমিটার?
  ক) ১.৮৫২ খ) ১.৬৫২ গ) ১.৯৬৩ ঘ) ১.৭৮৬
• ৭১. বিশ্বের ক্ষুদ্রতম রাজধানী কোনটি?
  ক) মোনাকো খ) কোনটিই নয় গ) ভ্যাটিকান সিটি ঘ) মানামা
• ৭২. তানসেনের অপর নাম কি?
  ক) রামতনু পান্ডে খ) হরিদাশ স্বামী গ) বিষ্ণু গোবিন্দ যোগ ঘ) জীবনানন্দ
• ৭৩. হকির যাদুকর কাকে বলা হয়?
  ক) ভাস্কর পিল্লাই খ) ধ্যানচাঁদ গ) শাহবাজ আহমেদ ঘ) মিলখা সিং
• ৭৪. হায়ারোগ্লিফিক হলো —
  ক) একটি মূর্তির নাম খ) একটি দেশের নাম গ) একটি জাতির নাম ঘ) একটি লিখন পদ্ধতির নাম
• ৭৫. নবায়নযোগ্য জ্বালানি কোনটি?
  ক) কয়লা খ) পরমাণু শক্তি গ) প্রাকৃতিক গ্যাস ঘ) পেট্রোল
• ৭৬. স্টিফেন হকিন্স বিশ্বের একজন বিখ্যাত —
  ক) পদার্থবিদ খ) কবি গ) রসায়নবিদ ঘ) দার্শনিক
• ৭৭. 'বাংলাদেশ স্কয়ার' কোন দেশে অবস্থিত?
  ক) সিয়েরালিওন খ) কানাডা গ) কঙ্গো ঘ) লাইবেরিয়া
• ৭৮. ময়নামতির পূর্ব নাম কি ছিল?
  ক) নদীয়া খ) হরিকেল গ) ত্রিপুরা ঘ) রোহিতগিরি
• ৭৯. সিন্দর এর অর্থ —
  ক) ঘুর্ণিঝড় খ) কান গ) চক্ষু ঘ) কোনটিই নয়
• ৮০. বিশ্বের সর্বাধিক ভাষার দেশ কোনটি?
  ক) যুক্তরাষ্ট্র খ) ভারত গ) চীন ঘ) পাপুয়া নিউগিনি
  Note: Papua New Guinea has over 800 languages — the most of any country in the world.