BEE (Bachelor of Electrical Engineering) Exam — Questions and Answers

Question 1: A transformer has 200 primary turns and 400 secondary turns. If the primary voltage is 120V, what is the secondary voltage?

60V
120V
240V (Correct answer)
480V

Correct answer: 240V

By the turns ratio formula V2/V1 = N2/N1, so V2 = 120 × (400/200) = 240V.

Question 2: The Superposition concept is upheld by .

Non-linear networks
Trilateral networks
Lateral networks
Linear networks (Correct answer)

Correct answer: Linear networks

The Superposition Theorem is a fundamental principle applicable only to linear circuits. It states that in a linear circuit with multiple independent sources, the total response (voltage or current) at any point is the sum of the responses caused by each independent source acting alone. This theorem relies on the properties of linearity, such as homogeneity and additivity.

Question 3: In an AC circuit, which of the following accurately depicts the average value?

RMS value*Form factor
RMS value/Peak factor
RMS value/Form factor (Correct answer)
RMS value*Peak factor

Correct answer: RMS value/Form factor

In an AC circuit, the form factor is defined as the ratio of the RMS (Root Mean Square) value to the average value of a waveform. Therefore, to find the average value, you can rearrange this relationship: Average Value = RMS Value / Form Factor. This formula allows for the calculation of the average value when the RMS value and form factor are known.

Question 4: Which type of ROM can be erased by exposing it to ultraviolet light?

Mask ROM
PROM
EPROM (Correct answer)
EEPROM

Correct answer: EPROM

EPROM (Erasable Programmable ROM) is erased by UV light shone through its quartz window, resetting all cells to 1.

Question 5: In an AC circuit, reactive power Q is measured in:

Watts (W)
Joules (J)
Volt-Ampere (VA)
Volt-Ampere Reactive (VAR) (Correct answer)

Correct answer: Volt-Ampere Reactive (VAR)

Reactive power, which represents energy oscillating between source and reactive elements, is measured in VAR.

Question 6: What does Ampère's circuital law with Maxwell's correction add to the original formulation?

Displacement current density ∂D/∂t (Correct answer)
Conduction current density
Electric polarization
Magnetic charge density

Correct answer: Displacement current density ∂D/∂t

Maxwell added the displacement current term ∂D/∂t to Ampère's law, enabling it to account for time-varying electric fields.

Question 7: What is the minimum number of two-input NAND gates required to implement an XOR function?

5
4 (Correct answer)
3
2

Correct answer: 4

An XOR gate can be constructed using exactly four two-input NAND gates.

Question 8: Which root locus rule states that the number of branches going to infinity equals the number of open-loop poles minus the number of open-loop zeros?

Centroid rule
Breakaway point rule
Angle of asymptotes rule
Number of asymptotes rule (Correct answer)

Correct answer: Number of asymptotes rule

The number of asymptotes (branches going to infinity) equals P − Z, where P is the number of poles and Z is the number of finite zeros.

Question 9: What is the purpose of a priority encoder?

To select one of many data inputs based on a binary address
To convert a decimal number to BCD
To generate a binary code corresponding to the highest-priority active input (Correct answer)
To detect and correct single-bit errors

Correct answer: To generate a binary code corresponding to the highest-priority active input

A priority encoder accepts multiple inputs and outputs a binary code representing the highest-priority (typically highest-numbered) active input, resolving conflicts when multiple inputs are asserted.

Question 10: Which sequential circuit type stores its current state in an array of flip-flops and uses combinational logic for next-state and output?

Finite state machine (Correct answer)
ROM lookup table
Ripple adder
Combinational PLA

Correct answer: Finite state machine

A finite state machine (FSM) consists of flip-flops holding the current state and combinational next-state/output logic driven by that state and inputs.

Question 11: In a hollow rectangular waveguide, which mode of propagation is characterized by having no electric field component in the direction of wave propagation and is typically the dominant mode?

Transverse Magnetic (TM)
Longitudinal Mode (LM)
Transverse Electromagnetic (TEM)
Transverse Electric (TE) (Correct answer)

Correct answer: Transverse Electric (TE)

Transverse Electric (TE) modes are characterized by the electric field vector being entirely perpendicular (transverse) to the direction of wave propagation. In standard rectangular waveguides, the TE10 mode has the lowest cutoff frequency and is therefore the dominant mode. TEM modes cannot propagate in a hollow single-conductor waveguide, and TM modes have a magnetic field that is entirely transverse.

Question 12: A technician is troubleshooting a Class B push-pull amplifier and observes distortion on the output waveform precisely at the zero-crossing point. What is the most likely cause of this issue?

Clipping distortion
Harmonic distortion
Crossover distortion (Correct answer)
Thermal runaway

Correct answer: Crossover distortion

Crossover distortion occurs in Class B amplifiers because there is a small region around the zero-crossing point where both transistors are turned off. This happens because the input signal must overcome the base-emitter voltage (around 0.7V for silicon transistors) before a transistor starts to conduct. This 'deadband' causes a flat spot on the output waveform as it crosses zero.

Question 13: For maximum power transfer in an AC circuit, what must be the relationship between the load impedance (ZL) and the Thevenin equivalent impedance (Zth) of the source network?

ZL = Zth
ZL is the complex conjugate of Zth (Correct answer)
ZL = -Zth
ZL is the reciprocal of Zth

Correct answer: ZL is the complex conjugate of Zth

The maximum power transfer theorem for AC circuits states that maximum power is delivered from a source to a load when the load impedance is the complex conjugate of the Thevenin (or source) impedance. If Zth = Rth + jXth, then for maximum power transfer, ZL must be Rth - jXth.

Question 14: When a system follows the laws of linear dynamics, it is referred to

scaling
both scaling and additivity (Correct answer)
additivity
homogeneity

Correct answer: both scaling and additivity

A system is considered linear if it satisfies two fundamental properties: additivity and homogeneity (also known as scaling). Additivity means that the response to a sum of inputs is the sum of the responses to individual inputs. Homogeneity means that scaling the input by a constant factor results in the output being scaled by the same factor. Both properties must hold for a system to be classified as linear.

Question 15: What does Norton's theorem state about a linear two-terminal network?

It can be replaced by a single equivalent resistor
It can be replaced by a current source in parallel with a resistance (Correct answer)
It can only be applied to DC circuits
It can be replaced by a voltage source in series with a resistance

Correct answer: It can be replaced by a current source in parallel with a resistance

Norton's theorem represents any linear two-terminal network as an equivalent current source in parallel with a resistance.

Question 16: What is the Poynting vector S for an electromagnetic wave with electric field E and magnetic field H?

H × E
E + H
E × H (Correct answer)
E · H

Correct answer: E × H

The Poynting vector S = E × H represents the directional power flux density of an electromagnetic wave.

Question 17: What is the primary architectural difference that distinguishes a Von Neumann architecture from a Harvard architecture in microprocessors?

The speed of the system clock.
The use of a RISC versus a CISC instruction set.
The organization of memory and buses for instructions and data. (Correct answer)
The number of processing cores available.

Correct answer: The organization of memory and buses for instructions and data.

The key difference lies in the memory structure. A Von Neumann architecture uses a single, shared memory and a common bus for both program instructions and data. In contrast, a Harvard architecture uses physically separate memories and separate buses for instructions and data, which allows the CPU to fetch an instruction and access data simultaneously, potentially overcoming the 'Von Neumann bottleneck'.

Question 18: Which of the following is a digital electronic example?

Digital cameras
Information appliances
Computers
All of the mentioned (Correct answer)

Correct answer: All of the mentioned

Digital electronics deals with devices that process information in discrete, binary formats. Digital cameras capture and store images as digital data, computers operate entirely on digital instructions and data, and information appliances like smartphones are essentially specialized digital computing devices. All these examples fundamentally rely on digital circuits and principles for their operation.

Question 19: In a DC transient RL circuit, how many time constants does it take for the current to reach approximately 99.3% of its steady-state value?

1τ
2τ
5τ (Correct answer)
3τ

Correct answer: 5τ

After 5 time constants (5τ = 5L/R), the current reaches 1 - e⁻⁵ ≈ 99.3% of its final value, considered practically at steady state.

Question 20: Which of the following describes the boundary condition for the tangential component of the electric field (E-field) at the surface of a perfect electrical conductor (PEC)?

It is continuous and non-zero across the boundary.
It is perpendicular to the surface.
It is equal to the surface charge density.
It must be zero. (Correct answer)

Correct answer: It must be zero.

At the surface of a perfect electrical conductor (PEC), the tangential component of the electric field must be zero (E_tan = 0). If a tangential component existed, it would exert a force on the free charges within the conductor, causing an infinite current to flow, which is not physically possible. Therefore, the E-field at the surface of a PEC can only have a normal component.

Question 21: In power systems, what is the difference between a 'bolted fault' and an 'arcing fault'?

A bolted fault is a sustained fault; an arcing fault is always transient and self-clearing
A bolted fault occurs at high voltage, while an arcing fault only occurs at low voltage
A bolted fault has zero impedance at the fault point producing maximum current; an arcing fault has arc impedance that limits current (Correct answer)
A bolted fault affects all three phases simultaneously; an arcing fault is always single-phase

Correct answer: A bolted fault has zero impedance at the fault point producing maximum current; an arcing fault has arc impedance that limits current

A bolted (solid) fault assumes zero fault impedance, giving the highest possible short-circuit current; arcing faults have arc resistance that reduces fault current below the bolted level.

Question 22: The torque T experienced by a magnetic dipole m in a uniform magnetic field B is:

T = B × m
T = m / B
T = m × B (Correct answer)
T = m · B

Correct answer: T = m × B

The torque is T = m × B, tending to align the magnetic moment with the applied field.

Question 23: What Boolean expression represents an Exclusive-OR (XOR) gate with inputs A and B?

A'B + AB' (Correct answer)
AB + A'B'
A + B
AB + A'B + AB'

Correct answer: A'B + AB'

XOR outputs 1 when the inputs differ: A'B (A=0,B=1) + AB' (A=1,B=0), written as A ⊕ B.

Question 24: A synchronous 3-bit up counter is currently in state 110. What is the next state?

101
000
011
111 (Correct answer)

Correct answer: 111

110₂ = 6; the next count is 7 = 111₂ in a standard 3-bit synchronous up counter.

Question 25: What type of circuit has outputs that depend on both current inputs and previous states?

Sequential circuit (Correct answer)
Combinational circuit
Arithmetic circuit
Analog circuit

Correct answer: Sequential circuit

Sequential circuits use memory elements so their outputs depend on both present inputs and past states.

Question 26: In the 8085 microprocessor, which register pair is used as the default stack pointer?

HL pair
BC pair
SP register (Correct answer)
DE pair

Correct answer: SP register

The 8085 has a dedicated 16-bit Stack Pointer (SP) register that holds the address of the top of the stack.

Question 27: In a common-emitter BJT amplifier, increasing the collector resistance RC while keeping other parameters fixed will:

Have no effect on voltage gain
Decrease input impedance
Increase voltage gain (Correct answer)
Decrease voltage gain

Correct answer: Increase voltage gain

Voltage gain Av = -gm·RC, so increasing RC directly increases the magnitude of voltage gain.

Question 28: An engineer is using a Karnaugh map (K-map) to simplify a 4-variable Boolean expression. What is the maximum number of adjacent '1's that can be grouped together to form a valid simplification term?

10
6
16 (Correct answer)
12

Correct answer: 16

In a K-map, groups must consist of a number of cells that is a power of two (1, 2, 4, 8, 16, etc.). For a 4-variable K-map, there are 2^4 = 16 cells. Therefore, the largest possible group would encompass all 16 cells, representing a constant function (either 1 or 0).

Question 29: In a CRO, the time base is generated by:

A square wave generator
A sawtooth wave generator (Correct answer)
A sinusoidal oscillator
A pulse generator

Correct answer: A sawtooth wave generator

The sawtooth (ramp) wave sweeps the electron beam linearly across the screen at a controlled rate to create the time axis.

Question 30: In phasor notation, multiplying a phasor by j (the imaginary unit) results in:

A 90° phase lead (Correct answer)
A 90° phase lag
Doubling the magnitude
Halving the magnitude

Correct answer: A 90° phase lead

Multiplying by j = 1∠90° rotates a phasor counterclockwise by 90°, corresponding to a 90° phase advance (lead).

Question 31: Which type of ROM can be erased by exposing it to ultraviolet light?

EPROM (Correct answer)
Flash
PROM
EEPROM

Correct answer: EPROM

EPROM (Erasable Programmable ROM) is erased by exposing it to UV light through a quartz window.

Question 32: A JK flip-flop is configured with both J and K inputs held high (connected to logic 1). If a clock signal is applied, what will be the behavior of the Q output?

The output state will be indeterminate.
The output will be permanently reset to 0.
The output will be permanently set to 1.
The output will toggle its state on each clock pulse. (Correct answer)

Correct answer: The output will toggle its state on each clock pulse.

When both J and K inputs of a JK flip-flop are held high, the flip-flop is in 'toggle' mode. In this mode, the output (Q) will invert its current state on the active edge of each clock pulse. This is a key feature that distinguishes the JK flip-flop from an SR flip-flop, as it provides a predictable outcome for the '1, 1' input condition.

Question 33: A second-order underdamped system has a damping ratio of 0.5. What is the approximate percent overshoot of its step response?

0%
25.4%
5.0%
16.3% (Correct answer)

Correct answer: 16.3%

Percent overshoot is calculated as e^(-πζ/√(1-ζ²)) × 100, which gives approximately 16.3% for ζ = 0.5.

Question 34: A TEM wave travels in the +z direction with E in the x-direction. The magnetic field H points in which direction?

+z direction
-y direction
+y direction (Correct answer)
+x direction

Correct answer: +y direction

For a +z-propagating wave with E in x̂, H = (1/η)(ẑ × E) points in the +ŷ direction.

Question 35: The CTFT of a rectangular pulse of width τ centered at the origin is:

A Gaussian function
Another rectangular pulse
A sinc function in frequency (Correct answer)
A complex exponential

Correct answer: A sinc function in frequency

The Fourier transform of a rectangular pulse rect(t/τ) is τ·sinc(fτ), a sinc function in the frequency domain.

Question 36: Which condition must hold for a system described by H(z) to be causal and stable?

All poles outside the unit circle
All zeros outside the unit circle
ROC excludes the unit circle
All poles inside the unit circle (Correct answer)

Correct answer: All poles inside the unit circle

A causal, stable discrete-time LTI system requires all poles to lie strictly inside the unit circle.

Question 37: A 12 V battery with an internal resistance of 0.5 ohms is connected to a 5.5 ohm external resistor. What is the terminal voltage?

6 V
11 V (Correct answer)
12 V
10 V

Correct answer: 11 V

Current = 12/6 = 2 A, and terminal voltage = 12 - (2 × 0.5) = 11 V.

Question 38: Which of the following is a characteristic of a minimum-phase system?

It cannot be stabilized by a proportional controller
It has the minimum possible phase lag for its magnitude response (Correct answer)
It has all poles and zeros in the right-half plane
Its Nyquist plot does not encircle the origin

Correct answer: It has the minimum possible phase lag for its magnitude response

A minimum-phase system has all poles and zeros in the left-half plane and exhibits the least phase lag achievable for a given magnitude response.

Question 39: What does a phase margin of 0 degrees indicate about a feedback control system?

The system has zero steady-state error
The system is on the verge of instability (Correct answer)
The system has infinite gain margin
The system is overdamped

Correct answer: The system is on the verge of instability

A phase margin of 0 degrees means the open-loop phase is exactly -180 degrees at the gain crossover frequency, placing the system at the boundary of instability.

Question 40: A capacitor of 100 µF is charged to 12 V. How much energy is stored in it?

600 µJ
1.2 mJ
14.4 mJ
7.2 mJ (Correct answer)

Correct answer: 7.2 mJ

E = ½CV² = ½ × 100×10⁻⁶ × 144 = 7.2×10⁻³ J = 7.2 mJ.

Question 41: The synchronous speed of a 4-pole induction motor operating on a 60 Hz supply is:

900 RPM
1800 RPM (Correct answer)
1500 RPM
1200 RPM

Correct answer: 1800 RPM

Synchronous speed Ns = 120f/P = 120 × 60 / 4 = 1800 RPM.

Question 42: In which number system is the addition 1011 + 1101 performed, and what is the result?

Hexadecimal; result is 18
Octal; result is 30
Decimal; result is 24
Binary; result is 11000 (Correct answer)

Correct answer: Binary; result is 11000

1011₂ (11) + 1101₂ (13) = 11000₂ (24) in binary arithmetic.

Question 43: The time constant (τ) of an RC circuit is:

R + C
C / R
R / C
R × C (Correct answer)

Correct answer: R × C

τ = RC (resistance × capacitance) in seconds.

Question 44: A JK flip-flop with J=1 and K=1 is in the SET state. After one clock pulse, what is the output?

Goes to RESET
Toggles to RESET (Correct answer)
Remains SET
Goes to invalid state

Correct answer: Toggles to RESET

When J=K=1, the JK flip-flop toggles its output on each clock pulse, so it moves from SET (Q=1) to RESET (Q=0).

Question 45: The rotor construction of a squirrel cage induction motor consists of:

Wound rotor with external resistance connections
Short-circuited aluminum or copper bars embedded in slots (Correct answer)
Copper windings connected to slip rings
Permanent magnets mounted on the rotor surface

Correct answer: Short-circuited aluminum or copper bars embedded in slots

A squirrel cage rotor has conducting bars (usually aluminum) embedded in rotor slots and short-circuited at both ends by end rings, requiring no external connections.

Question 46: The slew rate of an op-amp limits its ability to:

Handle DC offset voltages
Accurately reproduce high-amplitude, high-frequency signals (Correct answer)
Drive capacitive loads at low frequencies
Reject common-mode signals

Correct answer: Accurately reproduce high-amplitude, high-frequency signals

Slew rate (V/μs) limits the maximum rate of output voltage change, causing distortion when large-amplitude high-frequency signals demand faster output swings.

Question 47: Which semiconductor device is best suited for high-power, high-frequency RF amplification due to its superior electron mobility?

CMOS inverter
Silicon BJT
GaAs MESFET (Correct answer)
Silicon SCR

Correct answer: GaAs MESFET

GaAs MESFETs leverage GaAs's high electron mobility (~8500 cm²/V·s vs. Si's ~1400) for superior high-frequency performance.

Question 48: A linear phase FIR filter is preferred in applications requiring:

Recursive implementation
Maximum stopband attenuation
Minimum filter order
No phase distortion across all frequencies (Correct answer)

Correct answer: No phase distortion across all frequencies

Linear phase FIR filters introduce a constant group delay, preserving waveshape and avoiding phase distortion.

Question 49: In a purely resistive AC circuit, what is the phase angle between voltage and current?

180 degrees
45 degrees
90 degrees
0 degrees (Correct answer)

Correct answer: 0 degrees

In a purely resistive circuit, voltage and current are in phase, meaning the phase angle is zero degrees.

Question 50: What is the maximum power transfer condition for a DC circuit with a source resistance of 50 ohms?

Load resistance equals 50 ohms (Correct answer)
Load resistance equals 100 ohms
Load resistance equals 25 ohms
Load resistance is infinite

Correct answer: Load resistance equals 50 ohms

Maximum power is transferred when the load resistance equals the source resistance.

Question 51: In Boolean algebra, which law states that A + AB = A?

Absorption law (Correct answer)
Complement law
Associative law
Distributive law

Correct answer: Absorption law

The absorption law states A + AB = A because A already implies AB, so the redundant term AB is absorbed.

Question 52: In power system protection, what is the primary function of a protective relay?

To detect a fault or abnormal condition and send a trip signal to a circuit breaker. (Correct answer)
To step down high transmission voltages for measurement and monitoring.
To regulate the voltage at a specific bus by controlling reactive power.
To physically interrupt the flow of high fault currents in the circuit.

Correct answer: To detect a fault or abnormal condition and send a trip signal to a circuit breaker.

A protective relay is a sensing device that monitors electrical quantities like current, voltage, and frequency. When it detects an abnormal condition, such as a fault, its primary role is to operate its contacts to send a trip signal to a circuit breaker. The circuit breaker then performs the actual interruption of the circuit.

Question 53: Which type of ADC offers the fastest conversion speed?

Flash (parallel) ADC (Correct answer)
Sigma-delta ADC
Successive approximation ADC
Dual-slope ADC

Correct answer: Flash (parallel) ADC

A flash ADC uses 2ⁿ−1 comparators simultaneously to determine all bits at once, making it the fastest but most hardware-intensive ADC type.

Question 54: What is the purpose of a Schmitt trigger in digital circuits?

To store a single bit of data
To convert analog signals to digital with hysteresis for noise immunity (Correct answer)
To multiplex multiple input signals
To amplify weak digital signals

Correct answer: To convert analog signals to digital with hysteresis for noise immunity

A Schmitt trigger uses hysteresis with two different threshold voltages to provide clean digital output from noisy or slowly changing input signals.

Question 55: Which of the following correctly states Faraday's law in integral form?

∮E·dl = d/dt ∬D·dS
∮E·dl = -d/dt ∬B·dS (Correct answer)
∮E·dl = Q_enc/ε₀
∮E·dl = ∬J·dS

Correct answer: ∮E·dl = -d/dt ∬B·dS

Faraday's law states that the EMF around a closed path equals the negative rate of change of magnetic flux through the surface.

Question 56: How does the supply voltage affect a DC motor's response to an induce emf?

It will oppose the supply voltage (Correct answer)
It will aid the supply voltage
It will be half of the supply voltage
It will be double the supply voltage

Correct answer: It will oppose the supply voltage

When a DC motor's armature rotates within a magnetic field, it induces an electromotive force (emf) known as back emf. According to Lenz's Law, this induced back emf always acts in a direction that opposes the applied supply voltage. This opposition is crucial as it limits the armature current and helps regulate the motor's speed.

Question 57: Which of the following correctly describes the difference between discrete Fourier Transform (DFT) and the continuous Fourier Transform (CFT)?

DFT operates on continuous signals; CFT operates on discrete samples
DFT and CFT are identical for periodic signals
DFT produces a continuous spectrum; CFT produces a discrete spectrum
DFT operates on a finite number of samples and produces a periodic discrete spectrum (Correct answer)

Correct answer: DFT operates on a finite number of samples and produces a periodic discrete spectrum

The DFT takes N discrete-time samples and outputs N discrete frequency samples, effectively treating the signal as periodic with period N.

Question 58: Which of the following best describes the behavior of an inductor in a DC steady-state circuit?

It blocks AC but passes DC with high impedance
It acts as a capacitor
It acts as an open circuit
It acts as a short circuit (Correct answer)

Correct answer: It acts as a short circuit

In DC steady state, the inductor has no changing current, so its voltage drop is zero — it acts as a short circuit (wire).

Question 59: Which biasing configuration gives a BJT the highest input impedance?

Common emitter
Differential pair
Common collector (Correct answer)
Common base

Correct answer: Common collector

The common-collector (emitter-follower) configuration exhibits the highest input impedance among standard BJT configurations.

Question 60: What does the term 'fan-out' refer to in digital logic?

The speed at which signals propagate
The power dissipation per output
The maximum number of gate inputs that a gate output can reliably drive (Correct answer)
The number of inputs a gate can accept

Correct answer: The maximum number of gate inputs that a gate output can reliably drive

Fan-out specifies how many standard gate inputs the output of a given gate can drive while maintaining valid logic levels.

Question 61: The symmetrical components method decomposes an unbalanced three-phase phasor set into:

Line, phase, and neutral components
Positive, negative, and zero sequence components (Correct answer)
Active, reactive, and apparent components
Fundamental, harmonic, and DC components

Correct answer: Positive, negative, and zero sequence components

Fortescue's theorem shows any unbalanced three-phase system equals the superposition of positive-sequence, negative-sequence, and zero-sequence balanced phasor sets.

BEE (Bachelor of Electrical Engineering) Exam

The BEE (Bachelor of Electrical Engineering) Exam exam validates essential knowledge and skills required for certification or licensure in this field.

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