Elex refresh Flashcards
1
Q
- In the circuit, three resistors (R₁ = 10Ω, R₂ = 20Ω, R₃ = 30Ω) are connected in parallel across a 60V supply. What is the total current drawn from the supply?
A) 2A
B) 4A
C) 6A
D) 11A
A
D. 11
2
Q
- The Wheatstone Bridge is constructed having R1=80, R2=120, R3=480 and
R4=160 and source voltage 100V . Calculate the output voltage.
A) 60V
B) 25V
C) 35V
D) 85V
A
C. 35V
3
Q
- In the circuit, three resistors and two voltage sources are connected as follows:
Loop 1: 12V source, R1 = 6Ω, R2 = 4Ω (shared)
Loop 2: R2 = 4Ω (shared), R3 = 8Ω, 6V source
Using Node Voltage Method, what is the voltage at the shared node between R1,
R2, and R3 (assuming the bottom node is the reference ground)?
A) 4.08V
B) 5.08V
C) 6.08V
D) 8.08V
A
B
4
Q
- In the given circuit, two loops contain resistors and voltage sources:
Loop 1: 10V source, R1 = 5Ω, R2 = 10Ω (shared)
Loop 2: R2 = 10Ω (shared), R3 = 20Ω, 5V source
Using Mesh Analysis, what is the current I1 flowing in Loop 1?
A) 0.5A
B) 0.71A
C) 1A
D) 1.5A
A
B
5
Q
- In the circuit, the following elements are present:
Loop 1: A 12V voltage source, resistor R1 = 6Ω, shared resistor R2 = 4Ω.
Loop 2: Shared resistor R2 = 4Ω, resistor R3 = 8Ω, and a current-
dependent voltage source (2I1).
Using Mesh Analysis, what is the current I1 in Loop 1?
A) 1A
B) 1.5A
C) 2A
D) 2.5A
A
B
6
Q
- Which of the following theorems states that any linear electrical
network with voltage and current sources can be replaced by an
equivalent circuit consisting of a single voltage source and a series
resistance?
A) Superposition Theorem
B) Thevenin’s Theorem
C) Norton’s Theorem
D) Maximum Power Transfer Theorem
A
B
7
Q
- Which of the following statements best describes Superposition Theorem in
circuit analysis?
A) The total response in a linear circuit with multiple independent sources is
the sum of the individual responses caused by each source acting alone, with
all other sources replaced by their internal impedances.
B) Any linear circuit can be replaced by an equivalent voltage source in series
with a resistance.
C) The power delivered to a load is maximized when the load resistance
equals the Thevenin equivalent resistance of the circuit.
D) Any linear circuit can be replaced by an equivalent current source in
parallel with a resistance.
A
A
8
Q
- A 10V voltage source is connected in series with a 5Ω resistor (R1)
and a 10Ω resistor (R2). A load resistor (RL = 10Ω) is connected in
parallel with R2. What is the Thevenin equivalent voltage (Vth) seen by
the load resistor RL?
A) 3.33V
B) 5V
C) 6.67V
D) 7.5V
A
C
9
Q
- A series RC circuit consists of a 10V DC source, a 100kΩ resistor, and
a 10µF capacitor. At t = 0, the switch is closed, allowing the capacitor to
charge. What is the capacitor voltage Vc(t) at t = 2 seconds?
A) 3.68V
B) 5.0V
C) 6.32V
D) 8.65V
A
D
10
Q
- In the circuit, a 24V DC source is connected in series with two
resistors, R1 = 4Ω and R2 = 8Ω. A parallel branch contains R3 = 6Ω
connected across R2. What is the total current drawn from the 24V
source?
A) 2.5A
B) 3.2A
C) 4.1A
D) 6.7A
A
B
11
Q
- In the circuit, a 48V DC source is connected to three resistors:
R1 = 6Ω (in series with the source), R2 = 12Ω and R3 = 8Ω (connected in
parallel with each other).
What is the voltage drop across R1?
A) 18.33V
B) 26.67V
C) 30.25V
D) 36.75V
A
B
12
Q
- In the circuit, a 90V DC source is connected to a network containing:
R1 = 10Ω (in series with the source),
R2 = 20Ω (connected in parallel with a branch),
R3 = 30Ω (in series with R2 and connected in parallel with R4),
R4 = 40Ω (connected in parallel with R3).
What is the total current drawn from the 90V source?
A) 1.91A
B) 1.50A
C) 1.75A
D) 1.00A
A
A
13
Q
- A 120V (rms), 60Hz AC source is connected in series with:
R = 10Ω, X_L = 20Ω, X_C = 30Ω
Find the total current (I) flowing in the circuit.
A) 5.5A
B) 7.1A
C) 8.49A
D) 10.2A
A
C
14
Q
- A 230V (rms), 50Hz AC supply is connected to a series RLC circuit
consisting of:
(R) = 10Ω, (X_L) = 20Ω, (X_C) = 30Ω
Determine the real power (P) consumed by the circuit.
A) 2300W
B) 2500W
C) 2645W
D) 2800W
A
C
15
Q
- A 240V (rms), 50Hz AC source supplies power to a parallel RLC circuit
consisting of:
Branch 1: Resistor, R = 30Ω
Branch 2: Inductor with inductive reactance, X_L = 50Ω
Branch 3: Capacitor with capacitive reactance, X_C = 25Ω
Determine the total apparent power (S) supplied by the source.
A) 2100 VA
B) 2240 VA
C) 2500 VA
D) 2800 VA
A
B
16
Q
- A 120V (rms), 60Hz AC source is connected to a parallel circuit consisting of:
Branch 1: Resistor, R = 40Ω
Branch 2: Inductor with inductive reactance, X_L = 30Ω
Branch 3: Capacitor with capacitive reactance, X_C = 50Ω
Determine the total admittance (Y_total) of the circuit.
A) 0.030 - j 0.010 S
B) 0.025 - j 0.0133 S
C) 0.030 + j 0.015 S
D) 0.025 - j 0.0533 S
A
B
17
Q
- A 415V (rms), 50Hz AC source is connected to a parallel RLC circuit consisting of:
Branch 1: Resistor, R1 = 100Ω
Branch 2: Resistor, R2 = 150Ω
Branch 3: Inductor with inductive reactance, X_L1 = 120Ω
Branch 4: Inductor with inductive reactance, X_L2 = 80Ω
Branch 5: Capacitor with capacitive reactance, X_C = 90Ω
Determine the total impedance (Z_total) of the circuit in rectangular form.
A) 40.3 + j 22.7 Ω
B) 44.7 + j 26.1 Ω
C) 50.1 + j 30.5 Ω
D) 55.8 + j 35.0 Ω
A
B
18
Q
- A series RLC circuit is connected to a 120V (rms), 60Hz AC source.
The circuit consists of:
(R) = 20Ω, (L) = 50mH, (C) = 100μF
Determine the resonant frequency (f_r) of the circuit. (erroneous)
A) 190.5 Hz
B) 223.6 Hz
C) 260.7 Hz
D) 300.1 Hz
A
B
19
Q
- A parallel RLC circuit is connected to a 240V (rms), 50Hz AC source. The
circuit consists of:
(L) = 200mH
(C) = 20μF
(R) = 50Ω (connected in parallel with L and C)
Determine the bandwidth (BW) of the circuit at resonance.
A) 140.5 Hz
B) 150.2 Hz
C) 159.16 Hz
D) 175.3 Hz
A
C
20
Q
- A 230V (rms), 50Hz AC source supplies power to a series RLC circuit
consisting of:
(R) = 20Ω
(X_L) = 40Ω
(X_C) = 25Ω
Determine the reactive power (Q) consumed by the circuit.
A) Q = 1200 VAR
B) Q = 1270 VAR
C) Q = 1350 VAR
D) Q = 1400 VAR
A
B
21
Q
- A 230V (rms), 50Hz AC source supplies power to a series RL circuit consisting of:
(R) = 30Ω
(X_L) = 40Ω
To improve the power factor to 0.95 lagging, a capacitor is connected in parallel with the
load.
Determine the required capacitance (C) to achieve the desired power factor.
A) 32.5 μF
B) 45.2 μF
C) 38.4 μF
D) 50.8 μF
A
C
22
Q
- A two-port network has the following Z-parameters (impedance
parameters):
Z11 = 10Ω
Z12 = 5Ω
Z21 = 5Ω
Z22 = 20Ω
If the input voltage V1 = 50V and the output port is open-circuited, determine
the input current I1.
A) 3A
B) 6A
C) 5A
D) 4A
A
C
23
Q
- A two-port network has the following Y -parameters (admittance
parameters):
Y11 = 4 S
Y12 = -2 S
Y21 = -2 S
Y22 = 3 S
If the input current is I1 = 10A and the output is open-circuited,
determine the input voltage V1.
A) 3.75V
B) 5.2V
C) 4.5V
D) 2.8V
A
A
24
Q
- A two-port network has the following g-parameters (inverse hybrid
parameters):
g11 = 0.04 S
g12 = -0.002
g21 = 25
g22 = 8Ω
The network is connected to a load resistance of 16Ω at the output port.
If the input voltage is V1 = 50V, determine the output voltage V2.
A) 2400V
B) 2500V
C) 2600V
D) 2300V
A
B
25
Q
- A solid conductor is placed in a steady electrostatic field. What is the
electric field inside the conductor in electrostatic equilibrium?
A) It is equal to the external applied electric field.
B) It is zero.
C) It depends on the shape of the conductor.
D) It is nonzero but varies inside the conductor.
A
B
26
Q
- A long, straight conductor carries a steady current I. According to
Ampère’s Circuital Law, what is the magnetic field just outside the
surface of the conductor?
A) It is proportional to the square of the current.
B) It is directed parallel to the current inside the conductor.
C) It follows a circular path around the conductor.
D) It decreases exponentially with distance from the conductor.
A
C
27
Q
- When a dielectric material is placed
in an external electric field, how does it
respond?
A) The dielectric material generates free
charge carriers like a conductor.
B) The molecules in the dielectric align
with the electric field, reducing the
overall field inside.
C) The dielectric completely blocks the
external electric field.
D) The dielectric creates a stronger
electric field inside than the applied
field.
A
B
28
Q
- Which statement correctly describes the magnetic permeability of a material?
A) A material with high permeability allows magnetic fields to pass through it easily.
B) Magnetic permeability is always constant for every material.
C) A material with high permeability repels magnetic fields.
D) A vacuum has the highest magnetic permeability.
A
A
29
Q
- Two coils have self-inductances L1 = 4 H and L2 = 9 H, and the
coefficient of coupling k = 0.6. What is the mutual inductance M
between the coils?
A) 2.8 H
B) 4.2 H
C) 3.6 H
D) 5.0 H
A
C
30
Q
- A magnetic circuit consists of a coil with N = 500 turns, carrying a
current of 3A. The coil is wound around a core with a reluctance of 2000
A-turns/Wb. What is the energy stored in the magnetic field?
A) 500 J
B) 562.5 J
C) 600 J
D) 450 J
A
B
31
Q
- A parallel-plate capacitor with a plate area of 0.02 m² and plate separation
of 2 mm is connected to an AC source supplying a voltage that varies as V(t) =
50 sin(2π × 10⁶ t) V . The capacitor is filled with a dielectric material of
permittivity ε = 5ε₀ (ε₀ = 8.85 × 10⁻¹² F/m). Determine the displacement current
(I_d) in the capacitor.
A) 0.14A
B) 2.5A
C) 0.95A
D) 1.8A
A
A
32
Q
- A point charge of Q = 5 μC is placed at the center of a sphere of
radius 0.2 m in free space. Using Gauss’s Law, determine the electric
flux (Φ_E) through the sphere.
A) 4.50×10^5 N·m²/C
B) 5.65×10^5 N·m²/C
C) 6.20×10^5 N·m²/C
D) 0 N·m²/C
A
B
33
Q
- A positive clamping circuit is designed using an ideal diode and a
capacitor. The input signal is a sinusoidal wave with a peak-to-peak voltage of
10V, centered at 0V . What will be the DC shift in the output waveform after
passing through the clamping circuit?
A) +10V
B) +2.5V
C) +5V
D) 0V
A
C
34
Q
- A Zener diode with a Zener voltage of 6V is used in a voltage
regulator circuit. If the input voltage varies between 9V and 12V, and
the load remains constant, what will be the output voltage across the
load?
A) 9V
B) 6V
C) 7.5V
D) 12V
A
B
35
Q
- A red LED with a forward voltage of 2V is connected in series with a
330Ω resistor to a 9V DC power supply. What is the current flowing
through the LED when it is operating in forward bias? Assume the LED
operates ideally with no internal resistance.
A) 18.5mA
B) 25.0mA
C) 21.2mA
D) 30.0mA
A
C
36
Q
- A common-source amplifier using an NMOS transistor has the
following parameters:
Drain resistor (Rd) = 3.3 kΩ
Source resistor (Rs) bypassed by a capacitor
Transconductance (gm) = 5 mS
Output resistance of the transistor (ro) = 20 kΩ
Determine the small-signal output resistance (Rout) of the amplifier.
A) 3.50 kΩ
B) 2.83 kΩ
C) 1.80 kΩ
D) 4.00 kΩ
A
B
37
Q
- A common-source amplifier using an N-channel MOSFET has the
following circuit parameters:
Transconductance (gm) = 4 mS
Drain resistor (Rd) = 2.2 kΩ
Source resistor (Rs) = 500 Ω, bypassed by a capacitor
Assuming the MOSFET is operating in the saturation region, determine
the small-signal voltage gain (Av) of the amplifier.
A) -7.5
B) -10.2
C) -8.8
D) -5.6
A
C
38
Q
- A common-emitter amplifier uses a BJT with a DC current gain (β)
of 120 and a small-signal voltage gain (Av) of -50. The transistor has a
unity-gain frequency (fT) of 200 MHz. Determine the -3 dB bandwidth
of the amplifier
A) 6 MHz
B) 2.5 MHz
C) 4 MHz
D) 10 MHz
A
C
39
Q
- You are designing a common-source amplifier using an N-channel
MOSFET to achieve a small-signal voltage gain of -20. The available
circuit components are:
Drain resistor (Rd) = 4.7 kΩ
Source resistor (Rs) is bypassed by a capacitor
MOSFET transconductance (gm) needs to be selected
Determine the required transconductance (gm) value to achieve the
desired voltage gain.
A) 5.00 mS
B) 4.26 mS
C) 3.80 mS
D) 6.10 mS
A
B
40
Q
- A silicon diode is operating at a DC bias current (ID) of 1 mA.
Assuming the thermal voltage (VT) is 25 mV, what is the small-signal
resistance (rd) of the diode in its equivalent circuit?
A) 50Ω
B) 25Ω
C) 10Ω
D) 100Ω
A
B
41
Q
- A full-wave voltage doubler is connected to an AC source with an
RMS voltage of 15V . Assuming ideal diodes and capacitors, what will
be the DC output voltage of the circuit?
A) 30V
B) 42.42V
C) 15V
D) 21.21V
A
B
42
Q
- A capacitor filter is added to the output of a full-wave rectifier to reduce
ripple voltage and provide a smoother DC output. If the unfiltered peak DC
voltage is 30V, what is the expected approximate DC output voltage after
filtering under light load conditions?
A) 30V
B) 15V
C) 24V
D) 20V
A
A
43
Q
- A BJT (NPN transistor) is biased with the following voltages:
Base-emitter voltage (Vbe) = 0.7V
Collector-emitter voltage (Vce) = 1V
Assuming proper base current is supplied, in which operating region
is the transistor?
A) Cutoff Region
B) Active Region
C) Saturation Region
D) Breakdown Region
A
B
44
Q
- Which of the following statements correctly describes a key difference
between a MOSFET and a BJT?
A) MOSFETs have lower input impedance than BJTs.
B) BJTs are voltage-controlled, while MOSFETs are current-controlled.
C) A BJT is current-controlled, while a MOSFET is voltage-controlled.
D) BJTs are more efficient for high-speed switching applications than
MOSFETs.
A
C
45
Q
- A N-channel MOSFET operates with the following conditions:
Gate-to-source voltage (Vgs) = 6V
Threshold voltage (Vth) = 2V
Drain-to-source voltage (Vds) = 3V
In which operating region is the MOSFET functioning?
A) Saturation Region
B) Cutoff Region
C) Triode Region
D) Breakdown Region
A
C
46
Q
- Which of the following describes the effect of increasing
temperature on a silicon Bipolar Junction Transistor (BJT)?
A) Vbe increases, and leakage current decreases.
B) Vbe decreases, and leakage current increases.
C) β increases, and power dissipation decreases.
D) Temperature has no effect on a BJT’s performance.
A
B
47
Q
- In a common-emitter amplifier, a bypass capacitor (Ce) is often
connected in parallel with the emitter resistor (Re). What is the main
function of this bypass capacitor in the circuit?
A) It stabilizes the DC operating point.
B) It increases the voltage gain by bypassing the emitter resistor for
AC signals.
C) It improves high-frequency response by blocking AC signals.
D) It decreases the voltage gain by bypassing the emitter resistor for
AC signals.
A
B
48
Q
- A common-emitter amplifier using a BJT has a parasitic capacitance (Cbc)
between the collector and base terminals. This capacitance is referred to as
Miller capacitance when analyzing the amplifier’s high-frequency response.
How does the Miller capacitance affect the -3 dB bandwidth of the amplifier?
A) It increases the bandwidth by reducing the input capacitance.
B) It reduces the bandwidth by increasing the effective input capacitance.
C) It has no effect on frequency response.
D) It decreases gain but does not affect bandwidth.
A
B
49
Q
- A common-source MOSFET amplifier has the following parameters:
Gate-drain capacitance (Cgd) = 2 pF
Gate-source capacitance (Cgs) = 4 pF
Voltage gain (Av) = -40
Input resistance (Rin) = 100 kΩ
Output resistance (Rout) = 10 kΩ
Using the Miller approximation, determine the upper cutoff frequency (fH) of
the amplifier. Assume no other significant parasitic capacitances.
A) 185 kHz
B) 90 kHz
C) 250 kHz
D) 50 kHz
A
A
50
Q
- A common-emitter amplifier has the following parameters:
Voltage gain (Av) = -100
Upper cutoff frequency (fH) = 500 kHz
Given that the amplifier exhibits a first-order roll-off of -20 dB/decade,
determine the voltage gain (Avf) at 2 MHz.
A) -25.1
B) 10.2
C) +25.1
D) -10.2
A
A
51
Q
- A cascode amplifier consists of a common-emitter (CE) stage followed by a
common-base (CB) stage using BJTs. Compared to a single-stage common-
emitter amplifier, what is the main advantage of using a cascode configuration?
A) It provides higher voltage gain by stacking transistors.
B) It improves bandwidth by reducing the Miller effect.
C) It increases the input impedance significantly.
D) It eliminates the need for biasing resistors.
A
B
52
Q
- A two-stage cascade amplifier consists of two common-emitter (CE) stages
connected in series. Each stage has the following parameters:
Voltage gain of the first stage (Av1) = -30
Voltage gain of the second stage (Av2) = -25
Assuming ideal coupling between stages (no loading effects), determine the
overall voltage gain (Av_total) of the cascade amplifier.
A) -750
B) 750
C) -55
D) 30
A
B
53
Q
- A current mirror circuit is used in an amplifier design to provide a stable
biasing current. The circuit consists of two identical NPN BJTs (Q1 and Q2) with
their bases and emitters connected together. The reference transistor Q1 has a
set current of 100 μA. Assuming the transistors are perfectly matched and
neglecting base currents, what will be the collector current (Ic) of Q2 in the
current mirror?
A) 200 μA
B) 50 μA
C) 100 μA
D) 10 μA
A
C
54
Q
- A differential amplifier is designed with the following parameters:
Differential gain (Ad) = 2000
Common-mode gain (Acm) = 5
What is the common-mode rejection ratio (CMRR) in dB for this amplifier?
A) 45 dB
B) 60 dB
C) 52 dB
D) 40 dB
A
C
55
Q
- An inverting operational amplifier (op-amp) circuit is designed with the
following parameters:
Input voltage (Vin) = -0.5V
Feedback resistor (Rf) = 100 kΩ
Input resistor (Rin) = 20 kΩ
Assuming an ideal op-amp, determine the output voltage (Vout).
A) -2.5V
B) 5V
C) 2.5V
D) -5V
A
C
56
Q
- In an amplifier circuit, a portion of the output signal is fed back to
the input using a negative feedback network. What is the primary
effect of negative feedback on the amplifier’s performance?
A) It significantly increases the voltage gain.
B) It stabilizes the gain and reduces distortion.
C) It decreases the amplifier’s bandwidth.
D) It eliminates the need for biasing components.
A
B
57
Q
- A phase-shift oscillator uses a resistor-capacitor (RC) network to
generate a sine wave. If the circuit has:
Resistors (R) = 10 kΩ
Capacitors (C) = 0.01 μF
Determine the oscillation frequency (fosc) of the oscillator.
A) 500 Hz B) 649 Hz C) 1 kHz D) 250 Hz
A
B
58
Q
- A first-order low-pass RC filter is designed with:
Resistor (R) = 10 kΩ
Capacitor (C) = 0.01 μF
Determine the cutoff frequency (fc) of the filter.
A) 3.2 kHz
B) 500 Hz
C) 1.59 kHz
D) 10 kHz
A
C
59
Q
- A negative feedback system using an operational amplifier (op-amp) has
an open-loop gain (Aol) of 10^5 and a closed-loop gain (Acl) of 50. The system
also has a gain crossover frequency (fc) of 10 MHz, where the open-loop gain
falls to 1.
Determine the phase margin of the system if the phase shift at the gain
crossover frequency is -135°
. Based on this result, determine whether the
system is stable.
A) PM = 30°
, system is unstable
B) PM = 45°
, system is stable
C) PM = 60°
, system is critically stable
D) PM = 0°
, system is on the verge of oscillation
A
B
60
Q
- You are designing a Wien Bridge Oscillator to generate a sine wave at 1
kHz. To achieve sustained oscillation, determine the appropriate values of R
and C for the RC network, assuming standard component values.
A) R = 16 kΩ, C = 10 nF
B) R = 10 kΩ, C = 10 nF
C) R = 20 kΩ, C = 10 nF
D) R = 16 kΩ, C = 1 μF
A
A
61
Q
- A Silicon-Controlled Rectifier (SCR) is used as a switching device in
a DC motor control circuit. The SCR has anode, cathode, and gate
terminals. Which of the following conditions must be met to turn ON
the SCR and allow current to flow from anode to cathode?
A) Anode must be negative, and gate current must be applied.
B) Anode must be positive relative to cathode, and gate current must
be applied.
C) Gate current alone is sufficient to turn ON the SCR at any voltage.
D) Anode must be positive, but gate current is not necessary for
triggering.
A
B
62
Q
- A Unijunction Transistor (UJT) relaxation oscillator is designed with
the following circuit parameters:
Supply voltage (Vcc) = 12V
Resistor (R) = 100 kΩ
Capacitor (C) = 0.01 μF
Intrinsic standoff ratio (η)= 0.7
Determine the approximate oscillation frequency (fosc) of the circuit.
A) 500 Hz
B) 1.2 kHz
C) 831 Hz
D) 300 Hz
A
C
63
Q
- A photodiode is a semiconductor device that converts light energy
into an electrical current. It is commonly used in light sensors, optical
communication systems, and automatic brightness controls.
How does a photodiode operate when exposed to light?
A) It generates electron-hole pairs in the depletion region, increasing
reverse current.
B) It blocks all current flow when exposed to light.
C) It emits photons when a voltage is applied.
D) It works only in forward bias, increasing forward current with light
intensity.
A
A
64
Q
- In a data acquisition system (DAQ), a sensor (transducer) converts a
physical parameter (e.g., temperature, pressure, or displacement) into an
electrical signal. However, the raw signal from the sensor often requires
signal conditioning before it can be processed by an analog-to-digital
converter (ADC). What is the primary function of a signal conditioning
circuit in a data acquisition system?
A) It modifies and improves the sensor signal by amplification, filtering,
and level shifting
B) It directly converts a sensor signal into digital data without modification.
C) It stores the raw sensor signal for later processing.
D) It generates a reference voltage for the ADC but does not process the
sensor signal.
A
A
65
Q
- A Programmable Logic Controller (PLC) uses timers to control the
timing of operations in an industrial automation process. Which of the
following best describes the function of a timer in a PLC?
A) A PLC timer delays or measures time-based operations before
activating or deactivating an output.
B) A PLC timer continuously generates pulses to control a stepper
motor.
C) A PLC timer permanently stores data in non-volatile memory.
D) A PLC timer counts input pulses to determine frequency.
A
A
66
Q
- A building management system (BMS) is designed to improve energy efficiency by
controlling lighting based on occupancy. A motion-activated lighting system is to be
installed in a commercial building’s hallways and conference rooms. The system uses:
▪ Passive Infrared (PIR) motion sensors to detect human presence.
▪ A Programmable Logic Controller (PLC) to process sensor inputs and control lighting.
▪ Timers to ensure lights remain ON for a preset duration after motion is detected.
The lighting should turn ON when motion is detected and remain ON for 5 minutes after
the last motion is sensed. If no motion is detected within that period, the lights should
automatically turn OFF to conserve energy. Which type of PLC timer should be used to
meet this requirement?
A) On-Delay Timer (TON)
B) Off-Delay Timer (TOF)
C) Retentive Timer (RTO)
D) Pulse Timer (TP)
A
B
67
Q
- A commercial office building is implementing a smart HVAC (Heating, Ventilation,
and Air Conditioning) system that integrates with the Building Management System
(BMS) to improve energy efficiency and occupant comfort. The system consists of:
▪ Temperature and humidity sensors in each zone to monitor environmental conditions.
▪ Motorized dampers and variable air volume (VAV) units to adjust airflow dynamically.
▪ Programmable Logic Controllers (PLCs) to control the HVAC components.
▪ Occupancy sensors to detect room usage and adjust temperature accordingly.
During peak hours, the BMS detects that multiple zones are overheating, even though the
setpoints are correctly configured. The building automation dashboard shows that some
dampers remain partially closed, restricting airflow to critical areas. Which of the
following is the most likely cause of the issue?
A) Power supply issues in the HVAC system.
B) Faulty temperature sensors providing incorrect readings.
C) Mechanical failure or improper calibration of dampers.
D) Defective HVAC control logic in the PLCs.
A
C
68
Q
- A smart building integrates an emergency lighting system that must remain
functional during power failures. During routine testing, the BMS reports that
some emergency lights fail to turn ON during a simulated power outage, even
though the backup batteries are fully charged. Which fault detection method
would best identify the root cause of this failure?
A) Checking battery voltage only to confirm charge levels.
B) Using an automated self-test system that monitors battery health, wiring
integrity, and LED driver functionality.
C) Manually inspecting each emergency light once per year.
D) Waiting for a real power outage to identify faulty lights.
A
B
69
Q
- A logic circuit is designed using the Boolean expression: F(A, B, C)
= A • B + A • B’ • C
What is the simplified Boolean expression for F(A, B, C)?
A) A • (B + C)
B) A • B + C
C) A • B + B • C
D) A • B • C
A
A
70
Q
- A Boolean function is given as: F(A, B, C, D) = Σ(0, 1, 2, 5, 8, 9, 10, 13)
What is the simplified Boolean expression using a Karnaugh Map (K-map)?
A) B’ D’ + A’ C D + A B’ D
B) A D + B’ C D
C) A’ D + B C
D) B’ D’ + C’ D
A
D
71
Q
- You are given the Boolean function: F(A, B, C) = A • (B + C)
Your task is to design a circuit that implements this function using only
NAND gates. How many NAND gates implement this function?
A
D
72
Q
- A combinational circuit is designed to implement the function: F(A,
B, C) = Σ(1, 3, 5, 7)
Find the minimized Boolean expression.
A) F(A, B, C) = A B + C
B) F(A, B, C) = C
C) F(A, B, C) = A B + A C
D) F(A, B, C) = A + B + C’
A
B
73
Q
- A logic circuit is defined by the Boolean function: F(A, B, C) = (A + B)’ • C’
What is the equivalent simplified Boolean expression?
A) A’ + B’ + C’
B) A’ • B’ • C’
C) A + B + C
D) A • B • C
A
B
74
Q
- A Boolean function is given in Sum of Products (SOP) form:
F(A, B, C) = A B C’ + A’ B C + A B’ C
Using Boolean algebra, convert this SOP expression into its equivalent Product
of Sums (POS) expression.
A) (A’ + B’ + C’) • (A’ + B + C’) • (A + B’ + C’) • (A’ + B’ + C) • (A + B + C)
B) (A + B + C’) • (A + B’ + C) • (A’ + B’ + C’) • (A + B’ + C’) • (A’ + B + C)
C) (A’ + B + C) • (A + B’ + C) • (A’ + B’ + C’) • (A + B + C’) • (A + B + C)
D) (A’ + B + C’) • (A + B’ + C) • (A’ + B’ + C) • (A + B + C) • (A’ + B’ + C’)
A
C
75
Q
- How many gates would be required to implement the following
Boolean expression after simplification? XY + X(X + Z) + Y(X + Z)
A
B
76
Q
- A comparison between ring and johnson counters indicates that:
A) a ring counter has fewer flip-flops but requires more decoding
circuitry
B) a ring counter has an inverted feedback path
C) a johnson counter has more flip-flops but less decoding circuitry
D) a johnson counter has an inverted feedback path
A
D
77
Q
- A JK flip-flop is used in a synchronous sequential circuit where the clock
signal controls state transitions. Given the following conditions:
Current state Q = 1
J = 0, K = 1
Clock pulse is applied. What will be the next state Q(next)?
A) Next state: 0
B) Next state: 1
C) Next state: No change
D) Next state: Toggle
A
A
78
Q
- What type of register would shift a complete binary number in one
bit at a time and shift all the stored bits out one bit at a time?
A) PIPO
B) SISO
C) SIPO
D) PISO
A
B
79
Q
- Which of the following best describes the primary purpose of an
ASM chart?
A) Providing a structured approach to defining state transitions and
outputs in sequential circuits.
B) Representing a graphical method for designing purely
combinational logic circuits.
C) Converting complex analog circuits into digital logic-based
architectures.
D) Defining arithmetic operations like addition and subtraction using
logic gates.
A
A
80
Q
- Which of the following best explains why race conditions occur in
asynchronous circuits?
A) Race conditions occur when signal transitions reach different parts
of the circuit at different times, leading to unstable or incorrect states.
B) Race conditions occur only when using flip-flops that are not
properly synchronized with a clock signal.
C) Race conditions happen because asynchronous circuits cannot store
previous states in memory elements.
D) Race conditions result from using combinational logic instead of
sequential logic in digital circuits.
A
A
81
Q
- If the microprocessor is executing an arithmetic operation, which
unit is primarily responsible for processing the data?
A) Control Unit (CU)
B) Arithmetic and Logic Unit (ALU)
C) Registers
D) Memory Unit
A
B
82
Q
- What is the total addressable memory space for a 16-bit
microprocessor?
A) 16 KB
B) 64 KB
C) 128 KB
D) 32 KB
A
B
83
Q
- A 32-bit microprocessor initially has a 32-bit address bus. Due to
system requirements, the address bus is expanded to 36 bits. How
does increasing the address bus width from 32 bits to 36 bits affect the
total addressable memory space?
A) Increases addressable memory from 4 GB to 64 GB.
B) Increases addressable memory from 4 GB to 128 GB.
C) Increases addressable memory from 32 GB to 64 GB.
D) Doubles the addressable memory from 4 GB to 8 GB.
A
A
84
Q
- What is the primary purpose of cache memory in a
microprocessor-based system?
A) Providing temporary storage for all system data before writing to
main memory.
B) Reducing the average memory access time by storing frequently
used data closer to the processor.
C) Increasing the overall capacity of the main memory available to the
processor.
D) Replacing the need for main memory by acting as the primary
storage device.
A
B
85
Q
- How many unique IP addresses can be generated using IPv6?
A) (3.4 × 10³⁸) unique addresses
B) (4.3 × 10⁹) unique addresses
C) (1.28 × 10¹⁴) unique addresses
D) (6.4 × 10¹⁶) unique addresses
A
A
86
Q
- What is the primary function of an I/O subsystem in a
microprocessor-based system?
A) To enable communication between the microprocessor and external
devices.
B) To execute arithmetic and logical operations within the
microprocessor.
C) To store and retrieve data permanently for system memory.
D) To generate clock signals for synchronizing the microprocessor.
A
A
87
Q
- A 16-bit microprocessor uses memory-mapped I/O to interface
with external devices. The system has 64 KB of main memory, and an
I/O device is mapped to addresses from 0xF800 to 0xFBFF . What is the
total number of memory locations assigned to the I/O device?
A) 512 memory locations B) 2048 memory locations
C) 1024 memory locations D) 256 memory locations
A
C
88
Q
- What is the primary role of an Instruction Set Architecture (ISA) in a
microprocessor?
A) Determines how fast a processor executes instructions based on
clock cycles and power consumption.
B) Specifies the instructions a processor can execute and how it
interacts with memory and registers.
C) Defines the number of transistors in a processor and how they
process digital signals.
D) Controls how external I/O devices communicate with the processor
in a system.
A
B
89
Q
- Which of the following instructions correctly transfers the contents
of register A to memory location 0x2000?
A) MOV (0x2000), A B) MOV A, (0x2000)
C) MOV A, #0x2000 D) MOV 0x2000, A
A
A
90
Q
- What is the primary distinguishing feature of a microcontroller
compared to a general-purpose microprocessor?
A) Requires external memory and peripherals to function efficiently.
B) Optimized for performing complex mathematical calculations.
C) Integration of CPU, memory, and peripherals into a single chip.
D) Designed to execute general-purpose applications with an
operating system.
A
C
91
Q
- A company is developing a smart home automation system that requires a
microcontroller to control multiple sensors, wireless communication modules,
and low-power operation. The microcontroller must support Multiple GPIO
(General-Purpose Input/Output) pins to interface with sensors, low-power
consumption, built-in UART, I2C, and SPI for communication and flash memory
to store the embedded firmware. Given the following microcontroller options,
which one is the best choice for this application?
A) 8051 Microcontroller
Limited GPIOs, lacks built-in wireless communication support.
B) ATmega328P
Has multiple GPIOs, low power operation, and communication interfaces.
C) Intel 8086
Not a microcontroller, requires external peripherals.
Good for general embedded systems but lacks built-in wireless
D) PIC16F877A
capabilities.
A
B
92
Q
- A company is developing a battery-powered IoT sensor node for
environmental monitoring. The microcontroller must operate on low power
to maximize battery life, support wireless communication (Wi-Fi or
Bluetooth) for data transmission, have multiple ADC (Analog-to-Digital
Converter) channels to interface with temperature, humidity, and air
quality sensors and include sleep modes and wake-up interrupts to
reduce power consumption when idle. Given these requirements, which
microcontroller would be the best choice for this IoT sensor node design?
A) ATmega328P
Lacks built-in Wi-Fi or Bluetooth
B) ESP32
Best choice for IoT applications.
C) 8051 Microcontroller
Older architecture with no built-in Wi-Fi or Bluetooth
D) PIC16F877A
Lacks built-in Wi-Fi or Bluetooth
A
B
93
Q
- If a control system has forward gain G(s) = 10 / (s + 2) and
feedback gain H(s) = 1 / (s + 5), what is the closed-loop transfer
function T(s)?
A) 10(s + 5) / (s^2 + 7s + 20)
B) 10 / (s^2 + 7s + 20)
C) 10 / (s + 2)
D) 10(s + 2) / (s^2 + 7s + 20)
A
A
94
Q
- For a unit step input, the standard step response of a first-order system is
given by:
y(t) = K (1 - e^(-t/τ)). What does the time constant τ represent in the transient
response of this system?
A) The time required for the system output to reach exactly 100% of its final
value.
B) The time required for the system output to reach approximately 63.2% of its
final value.
C) The time required for the system output to complete one full oscillation.
D) The total time taken for the system to reach steady-state.
A
B
95
Q
- What is the primary purpose of a transfer function in system modeling?
A) It describes the input-output relationship of a system in the Laplace domain.
B) It provides the time-domain solution of a system’s response to any input.
C) It determines the physical components required to construct a control
system.
D) It directly calculates the steady-state output without solving for system
dynamics.
A
A
96
Q
- A second-order control system has the following transfer function:
H(s) = 10 / (s² + 4s + 25)
What is the damping ratio (ζ) of this system?
A) 0.8
B) 0.4
C) 0.2
D) 0.6
A
B
97
Q
- A control system has the following characteristic equation:
s³ + 5s² + 8s + 4 = 0
Determine whether the system is stable.
A) The system is unstable.
B) The system is marginally stable.
C) The system is stable.
D) The system has at least one right-half plane pole.
A
C
98
Q
- A control system has the following transfer function:
H(s) = (s + 5)(s - 2) / (s(s + 3)(s + 6))
Identify the poles and zeros of the system
A) Poles: s = -3, s = -6, s = 0; Zeros: s = -5, s = 2
B) Poles: s = 3, s = 6, s = 0; Zeros: s = 5, s = -2
C) Poles: s = -3, s = -6; Zeros: s = 0, s = 2
D) Poles: s = 2, s = -6; Zeros: s = -5, s = 0
A
A
99
Q
- Variation in circuit behavior with change in signal frequency. It can
also be considered as the variation of the gain and phase with
frequency.
A) frequency deviation
C) frequency response
B) phase gain
D) bode plot
A
C
100
Q
- It is a graphical method for examining how the roots of a system
change with variation of a certain system parameter, commonly a gain
within a feedback system.
A) Root Pole Analysis
B) Root Locus Analysis
C) Root Plant Method
D) Root Tree Analysis
A
B
