This is 100 items set of Practice Examination 11 in Electronics Engineering composed of previous and/or poterntial Board Exams Questions. Read each questions and choices carefully! Choose the best answer. In the actual board, you have to answer 100 items in Electronics Engineering within 5 hours. You have to get at least 70% to pass the subject. Electronics Engineering is 30% of the total 100% Board Rating along with Mathematics (20%), General Engineering and Applied Sciences (20%) and Electronics Systems and Technology (30%).
Start the Test Yourself Exam 11
Choose the letter of the best answer in each questions.
1. A power derating factor of 3.33 mW/°C above 50°C means that
- A. you must decrease the DC power dissipation rating by 3.33 mW for every 1°C rise in the operating temperature above 50°C
- B. you will end up getting a power of 3.33 mW if temperature goes beyond 50°C
- C. you must increase the DC power dissipation rating by 3.33 mW for every 1°C rise in the operating temperature above 50°C
- D. your zener diode will dissipate a nominal DC power of 3.33 mW for temperature above 50°C
ANS: A
2. When you first turn a power supply on, the filter capacitor initially acts as a short circuit thus creating a high initial current that can possibly destroy your rectifier diodes. What is the best way to limit the said current but without sacrificing the output voltage?
- A. use a large-value series current-limiting resistor
- B. use large-value filter capacitors
- C. use inductive filters instead of capacitive filters
- D. don’t turn off your power supply
ANS: C
3. The electromagnetic force induced between a varying magnetic field and a stationary conductor.
- A. Mutually induced EMF
- B. Self-induced EMF
- C. Electro statically induced EMF
- D. Statically induced EMF
ANS: D
4. A wire has a resistance of 5 Ω at room temperature and a temperature coefficient α = 4 × 10-3/°C. Calculate the wire resistance if the temperature rises by 75°C.
- A. 6.5 Ω
- B. 6.1 Ω
- C. 6 Ω
- D. 6.16 Ω
ANS: A
5. A combination of two charges with equal charge magnitude but opposite signs.
- A. magnetic dipole
- B. static dipole
- C. dynamic dipole
- D. electric dipole
ANS: D
6. If a dc electromagnetic of 10-V produces a steady-state current of 100-mA in a 100 Ω coil, how much will the current be after 0.2 sec?
- A. 63 mA
- B. 100 mA
- C. 37 mA
- D. 200 Ma
ANS: A
7. What is the time constant of a 20-H coil having 100 Ω of series resistance?
- A. 5 s
- B. 0.5 s
- C. 0.2 s
- D. 20 ms
ANS: C
8. If the RC time constant is given to be 1 s, how long will it take for the voltage to drop from 100 V to 50 V?
- A. 0.63 s
- B. 0.37 s
- C. 0.5 s
- D. 0.7 s
ANS: D
9. The effect of little change in magnetic flux density when magnetic field intensity increases.
- A. Retentivity
- B. Coercivity
- C. Saturation
- D. Permeability
ANS: C
10. A series resonant circuit at 0.2 MHz develops 100 mV across a 250 µH coil with a 2 mV input. Calculate Q.
- A. 50
- B. 25
- C. 100
- D. 200
ANS: A
11. A point in magnet where the intensity of magnetic lines of force is a maximum.
- A. North Pole
- B. Saturation Point
- C. Coercive point
- D. Magnetic pole
ANS: D
12. An oscillator circuit that has two capacitors and one inductor on its feedback network
- A. Colpitts
- B. Clapp
- C. Hartley
- D. Pierce Crystal
ANS: A
13. The ability of a substance of getting magnetized is called
- A. Retentivity
- B. Permeability
- C. Coercivity
- D. Susceptibility
ANS: D
14. A 12 volt battery is connected to a 5 cm, 350 turn coil with resistance of 15-Ω. What is the field strength produced in Oe?
- A. 70
- B. 280
- C. 56
- D. 353
ANS: A
15. A magnetic material has a relative permeability of 500. What is the absolute permeability of the material in cgs system?
- A. 500
- B. 630 H/m
- C. 500 G/Oe
- D. 630 x 10-6 G/Oe
ANS: C
16. The reciprocal of reluctance corresponds to what in electric circuits?
- A. Permeance
- B. Admittance
- C. Impedance
- D. Conductance
ANS: D
17. A material with negative temperature coefficient means
- A. Its resistance will increase as temperature increases
- B. Its resistance will decrease as temperature decreases
- C. Its resistance will increase as temperature decreases
- D. Its resistance will decrease as temperature increases
ANS: D
18. A 12-V battery with a capacity of 100 A-hr is used to supply 300-W electronic equipment and a 25 W light. How long will this battery last?
- A. 7.38 hours
- B. 3.69 hours
- C. 5.22 hours
- D. 2.61 hours
ANS: A
19. The physical motion that is due to the forces of magnetic fields
- A. Repulsion
- B. Attraction
- C. Motor Action
- D. Rotation
ANS: C
20. Which of these statements is FALSE about the relationship of the magnetic force on a moving charge?
- A. A magnetic force does not point in the direction of the field or in the direction of the charge’s velocity
- B. A magnetic force is exerted on a moving electric charge
- C. No magnetic force is exerted on a charge at rest
- D. A magnetic force is exerted on a charge moving along the direction of the magnetic field
ANS: B
21. Indicate which of the following statements is FALSE.
- A. Capacitive reactance is a measure of the reaction of C to a change in voltage
- B. RC time constant is a measure of the reaction of C to a change in voltage
- C. The concept of reactance is useful for both sine wave AC circuits and non-sinusoidal waveforms
- D. The method of time constant is used to analyze both sinusoidal and non-sinusoidal waveforms
ANS: C
22. It is the ability of an insulator to concentrate electric flux
- A. Permeability
- B. Susceptibility
- C. Permittivity
- D. Retentivity
ANS: C
23. It is commonly used for precision wire-wound resistors, which do not change resistance when the temperature increases
- A. carbon
- B. aluminum
- C. constantan
- D. iron
ANS: C
24. Which of the following statements is true about the force on a current-carrying straight conductor in a magnetic field?
- A. With the conductor at 90°, the reaction between two magnetic fields is minimum
- B. With the conductor at 0°, there is no effect between them
- C. With the conductor is at angle between 0° and 90°, only the parallel component is effective
- D. A motor action can be produced if the conductor is placed parallel to the magnetic field
ANS: B
25. It is known as the breakdown voltage of a dielectric material.
- A. relative permittivity
- B. dielectric strength
- C. velocity reduction ratio
- D. velocity factor
ANS: B
26. Find the value and tolerance of a resistor having bands of the following: Red, Violet, Green, Silver.
- A. 27 MΩ ±10%
- B. 2.7 MΩ ±10%
- C. 27 kΩ ±10%
- D. 2.7 kΩ ±10%
ANS: B
27. Thevenin’s theorem replaces a complicated circuit facing a load by an
- A. ideal voltage source and parallel resistor
- B. ideal voltage source and series resistor
- C. ideal current source and parallel resistor
- D. ideal current source and series resistor
ANS: B
28. In a sine wave AC circuit with inductive reactance, the
- A. phase angle of the circuit is always 45°
- B. voltage across the inductance must be 90° out of phase with the applied voltage
- C. current through the inductance lags its induced voltage by 90°
- D. current through the inductance and voltage across it are 180° out of phase
ANS: C
29. What negative feedback type increases both the input and output impedances of an amplifier?
- A. Voltage-shunt
- B. Current-shunt
- C. Voltage-series
- D. Current-series
ANS: D
30. A linear circuit is one whose parameters (e.g. resistances, etc)
- A. change with change in current
- B. change with change in voltage
- C. do not change with voltage and current
- D. are bilateral
ANS: C
31. Ten volts is applied across R1, R2, and R3 is series, producing 1 A in the series circuit. R1 equals 6 Ω and R2 equals 2 Ω. Therefore, R3 equals
- A. 2 Ω
- B. 10 Ω
- C. 4 Ω
- D. 12 Ω
ANS: A
32. A 0.5-C charge is moving at ratio of 5 cm/s. What is the current at 2 sec?
- A. 0.25 A
- B. 10 A
- C. 0.025 A
- D. 0.10 A
ANS: A
33. The fifth strip of a precision film resistor color code represents
- A. tolerance
- B. temperature
- C. failure rate
- D. multiplier
ANS: A
34. Find the value of a capacitor in picofarads having the following color bands: Yellow, Violet, Brown, Black, Yellow
- A. 47 pF ±10%
- B. 470 pF ±10%
- C. 47 pF ±20%
- D. 470 pF ±20%
ANS: D
35. A meter-sensitivity control in a test instrument would probably be:
- A. A set of switchable, fixed resistors
- B. A linear-taper potentiometer
- C. A logarithmic-taper potentiometer
- D. A wirewound resistor
ANS: B
36. At what temperature a magnetic material will lose its ferromagnetic properties?
- A. Curie temperature
- B. Absolute temperature
- C. ambient temperature
- D. room temperature
ANS: A
37. What is Coulomb’s first law of electrostatics?
- A. Like poles repel unlike poles attract each other
- B. Like charges repel unlike charges attract each other
- C. Unlike poles repel and like poles attract each other
- D. Unlike charges repel and like charges attract each other
ANS: B
38. A volume control in a stereo compact-disc player would probably be:
- A. A set of switchable, fixed resistors
- B. A linear-taper potentiometer
- C. A logarithmic-taper potentiometer
- D. A wirewound resistor
ANS: C
39. A conductor in which two oscillating circuit have the same resonant frequency is called
- A. Gimmick
- B. Synthony
- C. Puff
- D. Wet contact
ANS: B
40. The effect UV radiation that discharges a negatively charged body in a vacuum is called
- A. Joule effect
- B. Hallwachs effect
- C. Hall Effect
- D. Joshi effect
ANS: A
41. If a wire conductor of 0.1 resistance is doubled in length, its resistance becomes
- A. 0.01 Ω
- B. 0.02 Ω
- C. 0.2 Ω
- D. 0.05 Ω
ANS: C
42. On what basis is the size of the filter capacitor selected?
- A. short RC time constant
- B. power rating
- C. voltage rating
- D. long RC time constant
ANS: C
43. Those magnetic materials are best suited for making armature and transformer cores which have _____ permeability and ______ hysteresis loss.
- A. high, high
- B. high, low
- C. low, low
- D. low, high
ANS: B
44. A capacitor charged to 100 V and is then switched across a resistor. When the voltage across the capacitor has fallen to 14 V, the duration of the discharge as measured in time constants, is approximately
- A. 0.3
- B. 2.0
- C. 1.0
- D. 2.5
ANS: B
45. Preventing one material from affecting one another through their common electric or magnetic hysteresis
- A. grounding
- B. Hall Effect
- C. shielding
- D. limiting
ANS: C
46. If the tolerance color is violet, this means a tolerance of
- A. 0.1%
- B. 0.5%
- C. 0.25%
- D. 1%
ANS: A
47. A fully charged lead-acid battery will indicate a specific gravity reading between
- A. 1.175 to 1.200
- B. 1.225 to 1.250
- C. 1.200 to 1.225
- D. 1.275 to 1.300
ANS: D
48. Find the phase angle between the voltages across the current through the circuit when XC is 25 ohms, R is 100 ohms and XL is 100 ohms are in series.
- A. 53.1 degrees with the voltage lagging the current
- B. 36.9 degrees with the voltage leading the current
- C. 53.1 degrees with the voltage leading the current
- D. 36.9 degrees with the voltage lagging the current
ANS: D
49. For Kirchhoff’s voltage law, circuits are divided into which of the following?
- A. Series-parallel circuits
- B. Nodes
- C. Ohms
- D. Loops
ANS: D
50. The ability of a conductor to pass or the opposite of resistance?
- A. Reactance
- B. Capacitance
- C. Resistance
- D. Conductance
ANS: D
51. The resistance of a coil wire increases from 40 Ω at 10°C to 48.25 Ω at 60°C. Find the temperature coefficient at 0°C of the conductor material.
- A. 0.0043
- B. 0.00493
- C. 0.00393
- D. 0.0053
ANS: A
52. A length of wire has a resistance of 6 Ω. What is the resistance of wire of the same material three times as long as twice the cross-sectional area?
- A. 36 Ω
- B. 12 Ω
- C. 9 Ω
- D. 01 Ω
ANS: C
53. Which of the following statements is TRUE?
- A. An Ideal current source cannot be in parallel with a short circuit
- B. An ideal voltage source can be in parallel with an open circuit
- C. An ideal current source can be in series with an open circuit
- D. An ideal voltage source cannot be in series with an ideal current source
ANS: B
54. Halving the cross-sectional area of a conductor will
- A. Not affect the resistance
- B. Half the resistance
- C. Quarter the resistance
- D. Double the resistance
ANS: D
55. Given a power supply with a full load voltage of 200 volts and a regulation of 25%, what is the no load voltage?
- A. 150 volts
- B. 240 volts
- C. 160 volts
- D. 250 volts
ANS: D
56. A coil has 6,000 turns of wire and a resistance of 380 Ω. The coil is rewound with the same quantity (weight) of wire, but has 13,400 turns. How many Ω will the new coil have?
- A. 1895 Ω
- B. 1905 Ω
- C. 1825 Ω
- D. 1792 Ω
ANS: A
57. What is the average power dissipated by an electric heater with resistance of 50 Ω drawing a current of 20 sin 30t A?
- A. 0 kW
- B. 10 kW
- C. 14.14 kW
- D. 20 Kw
ANS: B
58. Those materials are well suited for making permanent magnets which have ______ retentivity and _____ coercivity.
- A. low, low
- B. high, high
- C. low, high
- D. high, low
ANS: B
59. A backwards-working electric motor is best described as:
- A. An inefficient, energy-wasting device
- B. A motor with the voltage connected the wrong way
- C. An electric generator
- D. A magnetic-field generator
ANS: C
60. What measurements are required to determine the phase angle of a single-phase circuit?
- A. The power in watts consumed by the circuit
- B. The frequency, capacitance and inductance
- C. The power in watts, voltage and current
- D. The resistance, current and voltage
ANS: C
61. An AC circuit consisting of a capacitor, an inductor and a resistor in series is a resonant when the
- A. in-phase current equals the out-of-phase current
- B. maximum current passes through the circuit
- C. power dissipation is minimum
- D. power factor is zero
ANS: B
62. What is the value of the peak factor for a pure sine wave?
- A. 1.414
- B. 0.637
- C. 0.707
- D. 1.11
ANS: A
63. The conductance and inductive susceptance of a circuit have the same magnitude. What is the power factor of the circuit?
- A. 1
- B. 0.707
- C. 0.5
- D. 0.866
ANS: B
64. A circuit has a resonant frequency of 455 KHz and a bandwidth of 57.2 KHz. Find the Q of the circuit.
- A. 795
- B. 79.5
- C. 0.795
- D. 7.95
ANS: D
65. In a parallel-resonant circuit, what is the relationship between impedance and current?
- A. Minimum impedance, minimum current
- B. Minimum impedance, maximum current
- C. Maximum impedance, minimum current
- D. Maximum impedance, maximum current
ANS: C
66. A 15 µC point charge is located on the y-axis at (0, 0.25). A second charge of 10 µC is located on the x-axis at (0.25, 0). If the two charges are separated by air, what is the force between them?
- A. 0.0982 N
- B. 33.93 N
- C. 0.341 N
- D. 10.79 N
ANS: D
67. A cell connection, providing a higher voltage than a single cell with no increase in current.
- A. Ground connected
- B. Parallel connected
- C. Series connected
- D. Series-parallel connected
ANS: C
68. A power transforming device, one that converts energy into some other form
- A. Converter
- B. Transducer
- C. Transformer
- D. Transmuter
ANS: D
69. Refers to charging and discharging of secondary cells?
- A. Re-charging of cell
- B. Re-aligning of cell
- C. Polarizing of cell
- D. Cycling of cell
ANS: D
70. What static electricity can be produced by rubbing fur on a rubber, amber, or plastic rod?
- A. Resinous static electricity
- B. Positive static electricity
- C. Vitreous static electricity
- D. Negative static electricity
ANS: A
71. What do you call the space between and around charged bodies?
- A. Magnetic field
- B. Electromotive force
- C. Electromagnetic field
- D. Electrostatic field
ANS: D
72. In RC circuits, the time constant indicates the time it takes a capacitor to charge up to what percent of the charging voltage?
- A. 100%
- B. 63%
- C. 67%
- D. 31%
ANS: B
73. A 0.01 m by 0.02m solar cell has a conversion efficiency of 9%. The maximum power rating of the device is
- A. 18 mW
- B. 180 mW
- C. 1800 kW
- D. 180 Kw
ANS: A
74. A practical type of capacitor used to demonstrate static electricity.
- A. Mycalex
- . Muller tube
- C. Geiger counter
- D. Leyden jar
ANS: D
75. What does a gold third band represent?
- A. 0.01 multiplier
- B. 5% tolerance
- C. a 10% tolerance
- D. a 0.1 multiplier
ANS: D
76. What does a fifth band on a resistor indicate?
- A. reliability
- B. sensitivity
- C. life
- D. no fifth band
ANS: B
77. DC motors and stepper motors are mainly used in robots instead of AC motors because they can
- A. be electronically controlled
- B. be operated by electric pulses
- C. withstand large overloads
- D. run at varying speed
ANS: B
78. The production of hydrogen gas caused by a portion of a charge current breaking down the water in the electrolytes
- A. Electrolysis
- B. Hydrogenation
- C. Hydrolysis
- D. Gassing
ANS: D
79. Length of twisted two-conductor cable used as a variable capacitive load in which, untwisting and separating the individual conductors vary the capacitance.
- A. Gimmick
- B. Syntony
- C. Puff
- D. Wet contact
ANS: A
80. The length of cylindrical capacitor is 10mm. The outer diameter of its single core cable conductor is 3 mm surrounded by a paper insulation of outer diameter 6 mm. What is its capacitance?
- A. 2.0 µF
- B. 2.5 µF
- C. 2.0 pF
- D. 2.5 Pf
ANS: C
81. What electrical quantity is measured by a watt-hour meter?
- A. Current
- B. Energy
- C. Voltage
- D. Power
ANS: B
82. The phenomenon whereby current in a gas changes as a result of irradiation by light is called
- A. Joule effect
- B. Hall Effect
- C. Joshi effect
- D. Hallwachs Effect
ANS: C
83. Three capacitors A, B and C are charged as follows: A = 10 µF at 100 V, B = 15 µF at 150 V and C = 25 µF at 200 V. They are then connected in parallel with terminals of like polarity together. What is the voltage across the combination?
- A. 156 V
- B. 256 V
- C. 165 V
- D. 265 V
ANS: C
84. A disadvantage of mercury cells and batteries is that:
- A. They don’t last as long as other types.
- B. They have a flat discharge curve.
- C. They pollute the environment.
- D. They need to be recharged often.
ANS: C
85. How long does it take for an initial charge of 20 VDC to decrease to 0.37 VDC in a 0.01 µF capacitor when a 2 MΩ resistor is connected across it?
- A. 0.08 second
- B. 0.4 second
- C. 0.6 second
- D. 0.2 second
ANS: A
86. If a resistance to which a constant voltage is applied is halved, what power dissipation will result?
- A. Doubled
- B. Quadrupled
- C. Halved
- D. Stay the same
ANS: A
87. A substance with high retentivity is best suited for making:
- A. An ac electromagnet
- B. A dc electromagnet
- C. An electrostatic shield
- D. A permanent magnet
ANS: D
88. A significant advantage, in some situations, of a toroidal coil over a solenoid is:
- A. The toroid is easier to wind
- B. The solenoid cannot carry as much current
- C. The toroid is easier to tune
- D. The magnetic flux in a toroid is practically all within the core
ANS: D
89. The process of converting chemical energy into electrical energy in a cell.
- A. Electron flow
- B. Electrolysis
- C. Polarization
- D. Electrochemical action
ANS: D
90. The portion of apparent power dissipated in a circuit
- A. Phase power
- B. True power
- C. Power factor
- D. Apparent power factor
ANS: B
91. Waves in alternating current can involve
- A. regular changes in voltages levels
- B. regular changes in current levels
- C. regular changes in the direction of the electron flow
- D. all of the above
ANS: D
92. In a triangular or sawtooth waveform, the RMS is how many times the peak value?
- A. 0.577
- B. 0.500
- C. 0.707
- D. 0.15
ANS: A
93. For an inductor or coil, which of the following indicates how low the losses are?
- A. Quality factor
- B. Inductive reactance
- C. Power factor
- D. Impedance
ANS: A
94. A certain wire has a resistance R. The resistance of another wire identical with the first except for having twice its diameter is
- A. 4R
- B. 2R
- C. R/2
- D. R/4
ANS: D
95. Copper is the second best conductor of electricity with ______ free electrons per in3.
- A. 1.68 x 1024
- B. 1.64 x 1024
- C. 1.6 x 1024
- D. 1.66 x 1024
ANS: B
96. A resistor with the color-coded value of 100 Ω and ±20 percent tolerance can have an actual resistance between
- A. 80 and 120 Ω
- B. 98 and 102 Ω
- C. 90 and 110 Ω
- D. 100 and 120 Ω
ANS: A
97. What is the basic purpose of all electrical and electronic system that are designed and built?
- A. to manipulate information
- B. to do work
- C. to do work and manipulate information
- D. to generate information
ANS: C
98. What is the typical leakage resistance of a paper capacitor?
- A. 109 Ω
- B. 105 Ω
- C. 1011 Ω
- D. 1010 Ω
ANS: A
99. Tantalum electrolytic capacitor has a typical value that ranges from
- A. 1 µF to 22000 µF
- B. 5 pF to 1 µF
- C. 1 µF to 1000 µF
- D. 1 nF to 100 µF
ANS: C
100. A transformer has 500 turns in the primary and 1500 in the secondary. Assuming no losses, if 45 V is applied to the primary what is the voltage developed in the secondary?
- A. 180 V
- B. 13.5 V
- C. 135 V
- D. 90 V
ANS: C
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