ELECTRICAL ENGINEERING DIPLOMA BASED 73 IMPORTANT MCQ PDF

1.The temperature, under thermal and electrical system analogy, is considered analogous to

(a) voltage
(b) current
(c) capacitance
(d) charge
(e) none of the above

Ans: a

2.In electrical-pneumatic system analogy the current is considered analogous to
(a) velocity
(b) pressure
(c) air flow
(d) air flow rate

Ans: d

3.In liquid level and electrical system analogy, voltage is considered analogous to
(a) head
(b) liquid flow
(c) liquid flow rate
(d) none of the above

Ans: a

4.The viscous friction co-efficient, in force-voltage analogy, is analogous to
(a) charge
(b) resistance
(c) reciprocal of inductance
(d) reciprocal of conductance
(e) none of the above

Ans: b

5.In force-voltage analogy, velocity is analogous to
(a) current
(b) charge
(c) inductance
(d) capacitance

Ans: a

6.In thermal-electrical analogy charge is considered analogous to
(a) heat flow
(b) reciprocal of heat flow
(c) reciprocal of temperature
(d) temperature
(e) none of the above

Ans: d

7.Mass, in force-voltage analogy, is analogous to
(a) charge
(b) current
(c) inductance
(d) resistance

Ans: c

8.In a stable control system backlash can cause which of the following ?
(a) Underdamping
(b) Overdamping
(c) Poor stability at reduced values of open loop gain
(d) Low-level oscillations

Ans: d

9.In an automatic control system which of the following elements is not used ?
(a) Error detector
(b) Final control element
(c) Sensor
(d) Oscillator

Ans: d

10.In a control system the output of the controller is given to
(a) final control element
(b) amplifier
(c) comparator
(d) sensor
(e) none of the above

Ans: a

11.A controller, essentially, is a
(a) sensor
(b) clipper
(c) comparator
(d) amplifier

Ans: c

12.The capacitance, in force-current analogy, is analogous to
(a) momentum
(b) velocity
(c) displacement
(d) mass

Ans: d

13.Which of the following devices are commonly used as error detectors in instruments ?
(a) Vernistats
(b) Microsyns
(c) Resolvers
(d) Any of the above

Ans: d

14.Which of the following should be done to make an unstable system stable ?
(a) The gain of the system should be decreased
(b) The gain of the system should be increased
(c) The number of poles to the loop transfer function should be increased
(d) The number of zeros to the loop transfer function should be increased

Ans: b

15.increases the steady state accuracy.
(a) Integrator
(b) Differentiator
(c) Phase lead compensator
(d) Phase lag compensator

Ans: a

16.A.C. servomotor resembles
(a) two phase induction motor
(b) Three phase induction motor
(c) direct current series motor
(d) universal motor

Ans: a

17.As a result of introduction of negative feedback which of the following will not decrease ?
(a) Band width
(b) Overall gain
(c) Distortion
(d) Instability

Ans: a

18.Regenerative feedback implies feedback with
(a) oscillations
(b) step input
(c) negative sign
(d) positive sign

Ans: d

19.The output of a feedback control system must be a function of
(a) reference and output
(b) reference and input
(e) input and feedback signal
(d) output and feedback signal

Ans: a

20.is an open loop control system.
(a) Ward Leonard control
(b) Field controlled D.C. motor
(c) Stroboscope
(d) Metadyne

Ans: b

21.A control system with excessive noise, is likely to suffer from
(a) saturation in amplifying stages
(b) loss of gain
(c) vibrations
(d) oscillations

Ans: a

22.Zero initial condition for a system means
(a) input reference signal is zero
(b) zero stored energy
(c) ne initial movement of moving parts
(d) system is at rest and no energy is stored in any of its components

Ans: d

23.Transfer function of a system is used to calculate which of the following ?
(a) The order of the system
(b) The time constant
(c) The output for any given input
(d) The steady state gain

Ans: c

24.The band width, in a feedback amplifier.
(a) remains unaffected
(b) decreases by the same amount as the gain increase
(c) increases by the sane saaaajajt as the gain decrease
(d) decreases by the same amount as the gain decrease

Ans: c

25.On which of the following factors does the sensitivity of a closed loop system to gain changes and load disturbances depend ?
(a) Frequency
(b) Loop gain
(c) Forward gain
(d) All of the above

Ans: d

26.The transient response, with feedback system,
(a) rises slowly
(b) rises quickly
(c) decays slowly
(d) decays quickly

Ans: d

27.The second derivative input signals modify which of the following ?
(a) The time constant of the system
(b) Damping of the system
(c) The gain of the system
(d) The time constant and suppress the oscillations
(e) None of the above

Ans: d

28.Which of the following statements is correct for any closed loop system ?
(a) All the co-efficients can have zero value
(6) All the co-efficients are always non-zero
(c) Only one of the static error co-efficients has a finite non-zero value
(d) None of the above

Ans: c

29.Which of the following statements is correct for a system with gain margin close to unity or a phase margin close to zero ?
(a) The system is relatively stable
(b) The system is highly stable
(c) The system is highly oscillatory
(d) None of the above

Ans: c

30.Due to which of the following reasons excessive bond width in control systems should be avoided ?
(a) It leads to slow speed of response
(b) It leads to low relative stability
(c) Noise is proportional to band width
(d) None of the above

Ans: c

31. Which is the lightest particle of an atom?
(a) Neutron
(b) Electron
(c) Proton
(d) All

Answer: Electron

32. Ampere second could be the unit of –
(a) Power
(b) Conductance.
(c) Energy
(d) Charge

Answer: Charge

33.The ratio of resistance of a 100W, 220V lamp to that of 100W lamp will be nearly-
(a) 4
(b) 8
(c) 1/4
(d) 1/2

Answer: 4

34.If the length and cross section of piece of conductor are both doubted what be its resistance(initial resistance R)?
(a) 4R
(b) 2R
(c) R
(d) 0.25R

Answer: 4R

35. The number of electron in the outermost orbit of carbon atom is ?
(a) 8
(b) 2
(c) 4
(d) 6

Answer: 4

36. Which one of the following semi-conductor ?
(a) Copper
(b) Silicon
(c) Neon
(d) Lithium

Answer: Silicon

37. For an R-L load-
(a) Active Power is better than apparent power
(b) Reactive Power is better than apparent power
(c) Apparent power is better than both active and reactive power
(d) All the equal

Answer: Apparent power is better than both active and reactive power

38.One Horse power is equal to –
(a) 5.50 foot pound/ second
(b) 55.00 foot pound/ second
(c) 550 foot pound/second
(d) 5550 foot pound/second

Answer: 550 foot pound/second

39. Satellite power requirement is provided through–
(a) Lead-acid batteries
(b) Dry cell
(c) Solar cells
(d) Nickel cadmium cell

Answer: Solar Cells

40.A radio station broadcast at 30m wavelength. The frequency of broadcast wiil be-
(a) 30Hz
(b) 300Hz
(c) 10MHz
(d) 10KHz

Answer: 10MHz

41.A short circuit test on transformer oil is-
(a) Copper loss at full load
(b) Copper loss at half load
(c) Iron loss at any load
(d) Sum of iron losses and copper losses

Answer: Copper loss at full load.

42.The type of oil which is suitable as transformer oil is-
(a) Animal oil
(b) Cooking oil
(c) Mineral oil
(d) Vegetable oil

Answer: Mineral Oil

43. Bucholz relay used on-
(a) Air cooled transformer.
(b) Oil cooled transformers.
(c) Welding transformers.
(d) Furnace transformer.

Answer: Oil cooled transformers.

44. Burden of current transformer is usually expressed in-
(a) Volts
(b) Amperes
(c) Volt amperes
(d) Kilowatt

Answer: Amperes

45. Which distribution system is more reliable?
(a) Ring main system
(b) Tree system
(c) Radial system
(d) All are equally reliable.

Answer: Ring main system.

46.Common declared distribution voltage in Bangladesh for low voltage circuit is –
(a) 230 Volt
(b) 440 Volt
(c) 250 Volt
(d)350 Volt

Answer: 230 Volt

47. The phenomena of creeping occurs in-
(a) Ammeter
(b) Voltmeter
(c) Wattmeter
(d) Watt-hour meter

Answer: Watt-hour meter

48.The unit of resistivity is
(a) Ohms
(b) Ohm-m
(c) Ohm/sqm
(d) None

Answer: Ohm-m

49. Three equal resistors of hundred ohm is connected in series across a source of E.m.f 30V.What would be the power consumed by is resistor?
(a) 10 W
(b) 30 W
(c) 90 W
(d) 60 W

Answer:10 W

50.What would be the charge of a uF when connected with 20V supply?
(a) 2000 uC
(b) 200 uC
(c) 300 uC
(d) 30 uC

Answer: 200 uC

51.Which power factor is more economical for the consumers-
(a) 0.85 Lagging
(b) 0.95 Lagging
(c) 0.10 Leading
(d) 0.85 Leading

Answer: 0.95 Lagging.

52. One Cubic water is equal to-
(a) 74.6 U.S Gallon
(b) 628 pound water
(c) 28.375 Line
(d) 28.3 Cubic meter

Answer: 28.3 Cubic meter

53. Active power is equal to-
(a) F Z
(b)VI Sin
(c)VI Cos
(d) None

Answer: VI Cos

54.Which is the used power factor improvement-
(a) Spring motor
(b) Commutator motor
(c) Synchronous motor
(d) Squirrel Case Motor

Answer: Synchronous motor.

55.If the power factor of a circuit is unity, its reactive power is-
(a) A maximum
(b) Equal to FR
(c) Zero
(d) A negative quantity

Answer: Zero

56.How can eddy current loss be minimized ?
(a)By using copper core
(b) By using solid core
(c) By laminating the core
(d) None of above

Answer: By laminating the core.

57.Dose the transformer draw any current when its secondary is open ?
(a) No
(b) Yes
(c) Take rated current
(d) None

Answer: Yes

58.A transformer has negative voltage regulation when its load power factor is-
(a) Zero
(b) Unity
(c) Leading
(d) Lagging

Answer: Leading

59. Permanent magnet is normally made of-
(a) Aluminum
(b) Wrought iron
(c) Cast iron
(d) Alnico alloys

Answer: Cast Iron

60. A carbon resistor contains
(a) carbon crystals
(b) solid carbon granules
(c) pulverized coal
(d) finely divided carbon black.

Ans: d

61. Which of the following materials does not have covalent bonds ?
(a) Organic polymers
(b) Silicon
(c) Metals

Ans: c

62. In graphite, bonding is
(a) covalent
(b) metallic
(c) Vander Waals
(d) Vander Waals and covalent

Ans: d

63. Total number of crystal systems is
(a) 2
(b) 4
(c) 7
(d) 12

Ans: c

64. The number of atoms per unit cell in B.C.C. structure is
(a) 1
(b) 2
(c) 4
(d) 8

Ans: b

65. The conductivity of a metal is determined by
(a) the electronic concentration and the mobility of the free electrons
(6) the number of valence electrons per atom
(c) either (a) or (b)
(d) none of the above

Ans: a

66. The resistivity of a metal is a function of temperature because
(a) the amplitude of vibration of the atoms varies with temperature
(b) the electron density varies with temperature
(c) the electron gas density varies with temperature

Ans: a

67. In a crystal, an atom vibrates at a frequency determined by
(a) the heat content of the crystal
(b) the temperature of the crystal
(c) the stiffness of the bonds it makes with neighbors

Ans: c

68. Due to which of the following reasons aluminium does not corrode in atmosphere ?
(a) Aluminium is a noble metal
(b) Atmospheric oxygen can only diffuse very slowly through the oxide layer which is formed on the surface of aluminium
(c) No reaction with oxygen occurs ft Any of the above

Ans: b

69. The impurity atoms is semiconductors
(a) inject more charge carriers
(6) reduce the energy gap
(c) increase the kinetic energy of valence electrons
(d) all of the above

Ans: b

70. Which of the following material is not a semiconductor ?
(a) Silica
(b) Germanium
(c) Selenium
(d) Gallium-arsenide

Ans: a

71. Carbon resistors are used extensively because they are
(a) easy to make
(b) compact
(c) inexpensive
(d) all of the above reasons

Ans: d

72. Carbon rods are used in wet and dry cells because
(a) carbon rod serves as conductor
(b) carbon can resist the attack of battery acid
(c) both (a) and (b)
(d) either (a) or (b)

Ans: c

73. Due to which of the following factors the brush wear rate is altered ?
(a) Speed of the machine
(b) Contact pressure
(c) Surface conditions of brush and commutator
(d) Excessive sparking
(e) All of the above

Ans: e