Explore topic-wise MCQs in Electrical Engineering Questions.

This section includes 214 Mcqs, each offering curated multiple-choice questions to sharpen your Electrical Engineering Questions knowledge and support exam preparation. Choose a topic below to get started.

51.

In the case of an unsymmetrical alternating current the average value must always be taken over__________?
A. unsymmetrical part of the wave form
B. the quarter cycle
C. the half cycle
D. the whole cycle
Answer» E.
Discussion
52.

In a series resonant circuit, the impedance of the circuit is___________?
A. minimum
B. maximum
C. zero
D. none of the above
Answer» B. maximum
Discussion
53.

Power factor of an inductive circuit is usually improved by connecting capacitor to it in____________?
A. parallel
B. series
C. either A. or (b)
D. none of the above
Answer» B. series
Discussion
54.

The voltage of domestic supply is 220V. This figure represents__________?
A. mean value
B. r.m.s. value
C. peak value
D. average value
Answer» B. r.m.s. value
Discussion
55.

A heater is rated as 230 V, 10 kW, A.C. The value 230 V refers to__________?
A. average voltage
B. r.m.s. voltage
C. peak voltage
D. none of the above
Answer» C. peak voltage
Discussion
56.

If two sine waves of the same frequency have a phase difference of JT radians, then_______?
A. both will reach their minimum values at the same instant
B. both will reach their maximum values at the same instant
C. when one wave reaches its maxi¬mum value, the other will reach its minimum value
D. none of the above
Answer» D. none of the above
Discussion
57.

The best place to install a capacitor is___________?
A. very near to inductive load
B. across the terminals of the inductive load
C. far away from the inductive load
D. any where
Answer» C. far away from the inductive load
Discussion
58.

Which of the following statements pertains to resistors only _____________?
A. can dissipate considerable amount of power
B. can act as energy storage devices
C. connecting them in parallel in¬creases the total value
D. oppose sudden changes in voltage
Answer» B. can act as energy storage devices
Discussion
59.

Aphasoris________?
A. a line which represents the magnitude and phase of an alternating quantity
B. a line representing the magnitude and direction of an alternating quantity
C. a coloured tag or band for distinction between different phases of a 3-phase supply
D. an instrument used for measuring phases of an unbalanced 3-phase load
Answer» B. a line representing the magnitude and direction of an alternating quantity
Discussion
60.

All definitions of power factor of a series R-L-C circuit are correct except__________?
A. ratio of net reactance and impedance
B. ratio of kW and kVA
C. ratio of J and Z
D. ratio of W and VA
Answer» B. ratio of kW and kVA
Discussion
61.

At very low frequencies a series R-C circuit behaves as almost purely___________?
A. resistive
B. inductive
C. capacitive
D. none of the above
Answer» D. none of the above
Discussion
62.

Wire-wound resistors are unsuitable for use at high frequencies because they_______?
A. create more electrical noise
B. are likely to melt under excessive eddy current heat
C. consume more power
D. exhibit unwanted inductive and capacitive effects
Answer» E.
Discussion
63.

A parallel AC. circuit in resonance will__________?
A. have a high voltage developed across each inductive and capacitive section
B. have a high impedance
C. act like a resistor of low value
D. have current in each section equal to the line current
Answer» C. act like a resistor of low value
Discussion
64.

The purpose of a parallel circuit resonance is to magnify________?
A. current
B. voltage
C. power
D. frequency
Answer» C. power
Discussion
65.

In AC. circuits, laminated iron is invariably used in order to__________?
A. reduce eddy current loss
B. increase heat radiation
C. make assembly cheap and easier
D. reduce circuit permeability
Answer» B. increase heat radiation
Discussion
66.

At _______ frequencies the parallel R-L circuit behaves as purely resistive
A. low
B. very low
C. high
D. very high
Answer» E.
Discussion
67.

The power is measured in terms of decibles in case of_________?
A. electronic equipment
B. transformers
C. current transformers
D. auto transformers
Answer» B. transformers
Discussion
68.

In an A.C. circuit power is dissipated in____________?
A. resistance only
B. inductance only
C. capacitance only
D. none of the above
Answer» B. inductance only
Discussion
69.

Skin effect occurs when a conductor carries current at_______ frequencies
A. very low
B. low
C. medium
D. high
Answer» E.
Discussion
70.

In a sine wave the slope is constant_______?
A. between 0° and 90°
B. between 90° and 180°
C. between 180° and 270°
D. no where
Answer» E.
Discussion
71.

In a parallel R-C circuit, the current always________the applied voltage?
A. lags
B. leads
C. remains in phase with
D. none of the above
Answer» C. remains in phase with
Discussion
72.

Which of the following refers to a parallel circuit ?
A. The current through each element is same
B. The voltage across element is in proportion to it’s resistance value
C. The equivalent resistance is greater than any one of the resistors
D. The current through any one element is less than the source current
Answer» E.
Discussion
73.

The phosphors for which of the following pair are 180° out of phase for VL, VC and VR______?
A. Vc and VR
B. VL and VR
C. Vc and VL
D. none of the above
Answer» D. none of the above
Discussion
74.

Ohm is unit of all of the following except___________?
A. inductive reactance
B. capacitive reactance
C. resistance
D. capacitance
Answer» E.
Discussion
75.

When an alternating current passes through an ohmic resistance the electrical power converted into heat is__________?
A. apparent power
B. true power
C. reactive power
D. none of the above
Answer» C. reactive power
Discussion
76.

The frequency of an alternating current is____________?
A. the speed with which the alternator runs
B. the number of cycles generated in one minute
C. the number of waves passing through a point in one second
D. the number of electrons passing through a point in one second
Answer» D. the number of electrons passing through a point in one second
Discussion
77.

The series and parallel resonance on L-C circuit’ differs in that_________?
A. series resistance needs a low-resistance source for sharp rise in current
B. series resonance needs a high-resistance source for sharp increase in current
C. parallel resonance needs a low-resistance source for a sharp in¬crease in impedance
D. parallel resonance needs a low-resistance source for a sharp rise in line current
Answer» B. series resonance needs a high-resistance source for sharp increase in current
Discussion
78.

Which of the following waves has the highest value of peak factor ___________?
A. Square wave
B. Sine wave
C. Half wave rectified sine wave
D. Triangular wave
Answer» D. Triangular wave
Discussion
79.

The r.m.s. value of half wave rectified sine wave is 200 V. The r.m.s. value of full wave rectified AC. will be___________?
A. 282.8 V
B. 141.4 V
C. 111 V
D. 100 V
Answer» B. 141.4 V
Discussion
80.

The inductance of a coil can be increased by_________?
A. increasing core length
B. decreasing the number of turns
C. decreasing the diameter of the former
D. choosing core material having high relative permeability
Answer» E.
Discussion
81.

The ratio of active power to apparent power is known as factor__________?
A. demand
B. load
C. power
D. form
Answer» D. form
Discussion
82.

The power factor at resonance in R-L- C parallel circuit is________?
A. zero
B. 0.08 lagging
C. 0.8 leading
D. unity
Answer» E.
Discussion
83.

In a three-phase supply floating neutral is undesirable because it way give rise to___________?
A. high voltage across the load
B. low voltage across the load
C. unequal line voltages across the load
D. minimun voltage across the load
Answer» D. minimun voltage across the load
Discussion
84.

An A.C. voltage is impressed across a pure resistance of 3.5 ohms in parallel with a pure inductance of impedance of 3.5 ohms?
A. the current through the resistance is more
B. the current through the resistance is less
C. both resistance and inductance carry equal currents
D. none of the above
Answer» D. none of the above
Discussion
85.

A pure capacitor connected across an A.C. voltage consumed 50 W. This is due to________?
A. the capacitive reactance in ohms
B. the current flowing in capacitor
C. the size of the capacitor being quite big
D. the statement is incorrect
Answer» E.
Discussion
86.

In a pure capacitive circuit if the supply frequency is reduced to 1/2, the current will__________?
A. be reduced by half
B. be doubled
C. be four times at high
D. be reduced to one fourth
Answer» B. be doubled
Discussion
87.

The product of apparent power and cosine of the phase angle between circuit voltage and current is
A. true power
B. reactive power
C. volt-amperes
D. instantaneous power
Answer» B. reactive power
Discussion
88.

The power factor of a D.C. circuit is always__________?
A. less than unity
B. unity
C. greater than unity
D. zero
Answer» C. greater than unity
Discussion
89.

In a pure inductive circuit if the supply frequency is reduced to 1/2, the current will__________?
A. be reduced by half
B. be doubled
C. be four times as high
D. be reduced to one fourth
Answer» C. be four times as high
Discussion
90.

The frequency of domestic power supply in Pakistan is_________?
A. 200 Hz
B. 100 Hz
C. 60 Hz
D. 50 Hz
Answer» E.
Discussion
91.

What will be the phase angle between two alternating waves of equal frequency, when one wave attains maximum value the other is at zero value________ ?
A. 0°
B. 45°
C. 90°
D. 180°
Answer» D. 180°
Discussion
92.

Capacitive susceptance is a measure of__________?
A. reactive power in a circuit
B. the extent of neutralisation of reactive power in a circuit
C. a purely capacitive circuit’s ability to pass current
D. a purely capacitive circuit’s ability to resist the flow of current
Answer» D. a purely capacitive circuit’s ability to resist the flow of current
Discussion
93.

The apparent power drawn by an A.C. circuit is 10 kVA and active power is 8 kW. The reactive power in the circuit is_________?
A. 4 kVAR
B. 6 kVAR
C. 8 kVAR
D. 16 kVAR
Answer» C. 8 kVAR
Discussion
94.

The effective resistance of an iron-cored choke working on ordinary supply frequency is more than its true resistance because of____________?
A. iron loss in core
B. skin effect
C. increase in temperature
D. capacitive effect between adjacent coil turns
Answer» B. skin effect
Discussion
95.

In an AC. circuit, a low value of kVAR compared with kW indicates_________?
A. low efficiency
B. high power factor
C. unity power factor
D. maximum load current
Answer» C. unity power factor
Discussion
96.

A pure inductance connected across 250 V, 50 Hz supply consumes 100 W. This consumption can be attributed to_________?
A. the big size of the inductor
B. the reactance of the inductor
C. the current flowing in the inductor
D. the statement given is false
Answer» E.
Discussion
97.

Time constant of an inductive circuit_________?
A. increases with increase of inductance and decrease of resistance
B. increases with the increase of inductance and the increase of resistance
C. increases with the decrease of inductance and decrease of resistance
D. increases with decrease of inductance and increase of resistance
Answer» B. increases with the increase of inductance and the increase of resistance
Discussion
98.

Time constant of a circuit is the time in seconds taken after the application of voltage to each___________?
A. 25% of maximum value
B. 50% of maximum value
C. 63% of maximum value
D. 90% of the maximum value
Answer» D. 90% of the maximum value
Discussion
99.

If a sinusoidal wave has frequency of 50 Hz with 30 A r.m.s. current which of the following equation represents this wave_________ ?
A. 42.42 sin 3141
B. 60 sin 25 t
C. 30 sin 50 t
D. 84.84 sin 25 t
Answer» B. 60 sin 25 t
Discussion
100.

If resistance is 20 Q. and inductance is 27 in a R-L series circuit, then time constant of this circuit will be________?
A. 0.001 s
B. 0.1 s
C. 10 s
D. 100 s
Answer» C. 10 s
Discussion