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| Engineering Reviewer - Electrical Circuits |
Electrical Circuits
51. Effects of capacitance
A. It opposes any change in the amount of voltage
B. Voltage is lagged behind the current by a quarter cycle
C. Electric energy is stored in the capacitor in the form of electrostatic field
D. All of the above
52. Points to be considered in choosing a capacitor
A. Working voltage
B. Type of dielectric
C. Capacitance
D. All of the above
53. Permeability is otherwise known as
A. Magnetic conductivity
B. Magnetic susceptibility
C. Electric conductivity
D. Electric susceptibility
54. The impedance in the study of electronics is represented by resistance and
A. Inductance
B. Capacitance
C. Inductance and capacitance
D. Reactance
55. Loop currents should be assumed to flow in which direction
A. Straight
B. Clockwise
C. Counter-clockwise
D. Either B or C arbitrarily selected
56. What determines the direction of induced emf in a conductor or coil?
A. Cork screw rule
B. Fleming’s left hand rule
C. Ampere’s circuital law
D. Fleming’s right hand rule
57. The reason why electrical appliances are connected in parallel.
A. It is a simple circuit
B. This makes the operation of appliances independent with each other
C. This results in reduced power consumption
D. All of the above
58. Which of the following does not affect resistance?
A. Resistivity
B. Cross-sectional area
C. Mass
D. Length
59. Which of the following is not considered a physical factor affecting resistance?
A. Length
B. Material type
C. Temperature
D. Cross-sectional
60. A 0.09 microfarad capacitor is charged to 220 volts. How long in milliseconds will it discharged resistor has a resistance of 20,000 ohms?
A. 1.5
B. 2.5
C. 1.25
D. 0.5
61. A trigger circuit consisting of a capacitor of 0.01 μF is connected in series with a resistor. If the circuit requires 100 Vdc to operate, determine the value of the resistor when time constant is 0.009s.
A. 900 Ω
B. 900 kΩ
C. 900 MΩ
D. 900 GΩ
62. The graph between an alternating quantity and time is called
A. Sine wave
B. Curve
C. Waveform
D. A plot
63. Which of the following is the most popular waveform?
A. Sinusoidal
B. Square wave
C. Triangular
D. Sawtooth
64. Which of the following does not refer to electrical energy?
A. Volt-ampere
B. Joule
C. Watt-second
D. Volt-coulomb
65. What is the resonant frequency of a circuit when L of 25 microhenrys and C of 10 picofarads are in parallel?
A. 10.1 kHz
B. 10.1 MHz
C. 101 MHz
D. 101 kHz
66. And ideal current source has an internal conductance of _____ siemen(s)
A. Infinite
B. One
C. Zero
D. One million
67. A capacitance of 6 µµF means
A. 6 pF
B. 6 nF
C. 6 fF
D. 6 aF
68. The voltage cannot be exactly in phase with the current in a circuit that contains
A. Only capacitance
B. Only resistance
C. Inductance and capacitance
D. Inductance, capacitance and resistance
69. The charge in the capacitor is stored at the
A. Terminals
B. Plates
C. Dielectric
D. Air
70. The reactance curve is a plot of frequency versus _____ for a series RLC circuit
A. Current
B. Voltage
C. Gain
D. Impedance
71. For a series circuit, the higher the quality factor
A. The greater the bandwidth
B. The narrower the passband
C. The broader the resonance curve
D. The wider the passband
72. “Any resistance R in a branch of a network in which a current I is flowing can be replaced by a voltage equal to IR”. This states
A. Compensation theorem
B. Reciprocity theorem
C. Millman’s theorem
D. Superposition theorem
73. The internal resistance of an ideal current source is
A. Infinite
B. Zero
C. Equal to the load resistance
D. To be determined
74. If three 100-pF capacitors are connected in series, then the total capacitance is
A. 300 pF
B. 100 pF
C. 50 pF
D. 33.3 pF
75. An inductance of 1 mH is
A. 0.001 H
B. 0.01 H
C. 0.0001 H
D. 0.10 H
76. A capacitor is basically constructed of
A. Two conductors separated by a dielectric
B. Two dielectric separated by a conductor
C. Conductors and dielectric
D. Conductors and semiconductors
77. In an inductive coil, the rate of rise of current is maximum
A. Near the final maximum value of current
B. At mid-value of current
C. At half-power points
D. After one time constant
78. Two complex numbers or phasors are said to be conjugate if they
A. Differ only in the algebraic sign of their quadratic components
B. Differ only in the algebraic sign of their real components
C. Are equal in their real and quadrature components including algebraic signs
D. Are equal in their real components but differ in their quadrature components including algebraic signs.
79. In an ac circuit with a resistive branch and an inductive branch in parallel, the
A. Voltage across the inductance leads the voltage across the resistance by 90°
B. Resistive branch current is 90° out of phase with the inductive branch current
C. Resistive and inductive branch currents have the same phase
D. Resistive and inductive branch currents are 180° out-of-phase
80. In an ac circuit with XL and R in series, the
A. Voltages across R and XL are in phase
B. Voltage across R lags the voltage across XL by 90°
C. Voltages across R and XL are 180° out-of-phase
D. Voltage across R leads the voltage across XL by 90°
81. Leakage resistance in a capacitor results into
A. Internal heating
B. Internal bleeding
C. Shorter useful life
D. Short-circuiting
82. Voltage resonance means
A. Series resonance
B. Parallel resonance
C. Current magnification
D. Gain magnification
83. The unit of elastance is
A. Farad
B. Daraf
C. Siemen
D. Henry
84. The farad is not equivalent to which of the following combination of units
A. C(V^2)
B. (C^2)/J
C. C/V
D. J/(V^2)
85. Which component opposes voltage change?
A. Resistor
B. Inductor
C. Capacitor
D. Transistor
86. What is the peak factor for alternating current or voltage varying sinusiodally?
A. 1.4142
B. 0.707
C. 0.636
D. 1.11
87. Which of the following is not a factor affecting dielectric strength?
A. Mass
B. Moisture content
C. Temperature
D. Thickness
88. The superposition theorem is used when the circuit contains
A. Reactive elements
B. Active elements
C. Number of voltage sources
D. Single voltage source
89. What refers to such work at very low temperatures, near absolute zero?
A. Cryogenics
B. Superconductivity
C. Subsonic
D. Thermionic
90. A factor that states how much the resistance changes for a change in temperature?
A. Resistivity
B. Specific resistance
C. Coefficient of temperature change
D. Temperature coefficient of resistance
91. An alloy composed of 84 % copper, 12 % manganese and 4 % nickel.
A. Manganin
B. Constantan
C. Nichrome
D. German silver wire
92. A law which states that when a constant electromotive force is applied to a circuit consisting of a resistor and capacitor connected in series, the time taken for the potential on the plates of the capacitor to rise to any given fraction of its final value depends only on the product of capacitance and resistance.
A. Child’s law
B. CR law
C. Coulomb’s law
D. Debye T3 law
93. At parallel resonance, the currents flowing through L and C are
A. Infinite
B. Zero
C. Unequal
D. Equal
94. In a rectangular wave, the peak factor is
A. 1.16
B. 1.73
C. 1.11
D. 1.0
95. In an RL series circuit,
A. Current lags voltage by less than 90˚
B. Current lags voltage by 180˚
C. Current lags voltage by 90˚
D. Current leads voltage by 90˚
96. In a pure capacitance,
A. Current leads voltage by 90˚
B. Current leads voltage by 180˚
C. Current lags voltage by 90˚
D. Current lags voltage by 180˚
97. The ohmic value of a resistor with negative temperature coefficient
A. Increases with increasing temperature
B. Increase with decreasing temperature
C. Stays unchanged with temperature change
D. Stays unaffected even with increasing temperature
98. Which of the statements below is not true?
A. Current source is an active element
B. Resistor is a linear element
C. Voltage source is a passive element
D. Diode is a non-linear element
99. Which of the following elements is active?
A. Resistor
B. Inductor
C. Capacitor
D. Ideal voltage source
100. What is the complex impedance of a circuit with an absolute resistance of 300 Ω?
A. 0 + j 300 Ω
B. 300 + j 90 Ω
C. 0 – j 300 Ω
D. 300 + j 0 Ω
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