Computer Engineering NEC License Exam | MCQs | Concept of Basic Electrical and Electronics Engineering

MCQs on Concept of Basic Electrical and Electronics Engineering | Nepal Engineering Council (NEC) | Registration Examination Computer Engineering | Mock Test

1. Concept of Basic Electrical and Electronics Engineering (AExE01) Syllabus

1.1 Basic concept: Ohm´s law, electric voltage current, power and energy, conducting and insulating
materials. Series and parallel electric circuits, start-delta and delta-star conversion, Kirchhoff’s law, linear and non-linear circuit, bilateral and unilateral circuits, active and passive circuits.
1.2 Network theorems: concept of superposition theorem, Thevenins theorem, Nortons theorem,
maximum power transfer theorem. R-L, R-C, R-L-C circuits, resonance in AC series and parallel circuit, active and reactive power.
1.3 Alternating current fundamentals: Principle of generation of alternating voltages and currents and their equations and waveforms, average, peak and rms values, Three phase system.
1.4 Semiconductor devices: Semiconductor diode and its characteristics, BJT Configuration and biasing, small and large signal model, working principle and application of MOSFET and CMOS.
1.5 Signal generator: Basic Principles of Oscillator, RC, LC and Crystal Oscillators Circuits, Waveform generators.
1.6 Amplifiers: Classification of Output Stages, Class A Output Stage, Class B Output Stage, Class AB
Output Stage, Biasing the Class AB Stage, Power BJTs, Transformer-Coupled Push-Pull Stages, and
Tuned Amplifiers, op-amps.

Part - 1

1. Basic Concept

Ohm's law states that the current through a conductor between two points is directly proportional to the:
- A) Voltage across the two points
- B) Resistance between the two points
- C) Power between the two points
- D) Energy between the two points
  Answer: A
The unit of electric power is:
- A) Joules
- B) Coulombs
- C) Watts
- D) Volts
  Answer: C
In a series circuit, the current:
- A) Varies with the resistance
- B) Is the same through each component
- C) Is different across each component
- D) Follows Kirchhoff's voltage law only
  Answer: B
Kirchhoff’s Current Law (KCL) states that:
- A) The total voltage around any closed loop is zero
- B) The sum of all currents entering a junction equals the sum of all currents leaving the junction
- C) The product of resistance and capacitance is zero
- D) The sum of power consumed equals the power generated
  Answer: B
A circuit with components that only contain resistors and inductors is considered:
- A) Active
- B) Passive
- C) Unilateral
- D) Non-linear
  Answer: B

2. Network Theorems

Superposition theorem applies to:
- A) Non-linear circuits
- B) Bilateral circuits only
- C) Linear circuits
- D) Unilateral circuits
  Answer: C
The Thevenin equivalent circuit consists of:
- A) A current source and parallel resistance
- B) A voltage source and series resistance
- C) A dependent voltage source and a resistor
- D) A voltage source and a parallel resistance
  Answer: B
Norton’s theorem is used to:
- A) Simplify circuits into a single voltage source and a resistor
- B) Simplify circuits into a current source and parallel resistor
- C) Analyze the power dissipation in a circuit
- D) Calculate the maximum power transfer
  Answer: B
For maximum power transfer, the load resistance should be:
- A) Equal to the source resistance
- B) Twice the source resistance
- C) Half the source resistance
- D) Zero
  Answer: A
Resonance in an AC circuit occurs when:
- A) The inductive reactance is equal to the capacitive reactance
- B) The resistance is equal to the capacitive reactance
- C) The inductance is zero
- D) The circuit is unilateral
  Answer: A

3. Alternating Current Fundamentals

The RMS value of an AC voltage is related to its peak value by:
- A) $V_{\text{rms}} = V_{\text{peak}} \times \frac{1}{\sqrt{2}}$
- B) $V_{\text{rms}} = V_{\text{peak}} \times 2$
- C) $V_{\text{rms}} = V_{\text{peak}} \times \sqrt{2}$
- D) $V_{\text{rms}} = V_{\text{peak}} \times 0.5$
  Answer: A
In a three-phase system, the phase difference between adjacent phases is:
- A) 30 degrees
- B) 60 degrees
- C) 120 degrees
- D) 180 degrees
  Answer: C
The average value of a sinusoidal AC signal over one complete cycle is:
- A) Equal to the RMS value
- B) Equal to the peak value
- C) Zero
- D) Equal to half the peak value
  Answer: C

4. Semiconductor Devices

A semiconductor diode conducts current when:
- A) It is reverse biased
- B) The anode is more positive than the cathode
- C) The cathode is more positive than the anode
- D) No voltage is applied
  Answer: B
In a BJT, the region of operation where both the base-emitter and base-collector junctions are forward-biased is called:
- A) Cutoff region
- B) Saturation region
- C) Active region
- D) Breakdown region
  Answer: B
A MOSFET differs from a BJT because:
- A) It is a current-controlled device
- B) It has no gate terminal
- C) It is a voltage-controlled device
- D) It does not have a drain terminal
  Answer: C

5. Signal Generators

The purpose of a crystal oscillator is to:
- A) Generate high-frequency signals with poor accuracy
- B) Generate low-frequency signals with high accuracy
- C) Generate stable and accurate frequencies
- D) Amplify weak signals
  Answer: C
An RC oscillator uses:
- A) Resistors and inductors
- B) Resistors and capacitors
- C) Inductors and capacitors
- D) Transistors and diodes
  Answer: B
Waveform generators are primarily used to:
- A) Amplify signals
- B) Generate different types of waveforms like sine, square, and triangular waves
- C) Filter out noise from signals
- D) Convert AC to DC
  Answer: B

6. Amplifiers

A Class A amplifier is characterized by:
- A) High efficiency and low linearity
- B) Low efficiency and high linearity
- C) Medium efficiency and medium linearity
- D) No power consumption at all
  Answer: B
A transformer-coupled push-pull stage is used to:
- A) Decrease signal distortion in power amplifiers
- B) Increase signal distortion in power amplifiers
- C) Generate oscillations
- D) Regulate voltage
  Answer: A
Op-amps are commonly used in:
- A) Signal generation
- B) Power transmission
- C) Signal amplification and processing
- D) Generating digital signals
  Answer: C

Part - 2

1. Basic Concept

In a parallel circuit, the voltage across each component:
- A) Is different
- B) Is zero
- C) Is the same
- D) Is double
  Answer: C
The unit of electrical energy is:
- A) Joules
- B) Watts
- C) Coulombs
- D) Ohms
  Answer: A
A linear circuit is defined as a circuit in which:
- A) The output is directly proportional to the input
- B) The output is exponentially related to the input
- C) The resistance varies with time
- D) The power dissipation changes with frequency
  Answer: A
The term “bilateral circuit” refers to a circuit where:
- A) The resistance is non-linear
- B) The circuit components have direction-dependent characteristics
- C) The current can flow in both directions
- D) The voltage and current are out of phase
  Answer: C
Active components in a circuit are defined as:
- A) Components that consume power
- B) Components that can amplify or switch signals
- C) Components that only pass signals without alteration
- D) Components that do not require power
  Answer: B

2. Network Theorems

The Thevenin equivalent circuit of a network is:
- A) A voltage source in series with a resistor
- B) A current source in parallel with a resistor
- C) A combination of capacitors and inductors
- D) A dependent voltage source and an inductor
  Answer: A
In an R-L-C series circuit at resonance:
- A) The impedance is maximum
- B) The impedance is minimum
- C) The reactance is zero
- D) The resistance equals the inductive reactance
  Answer: B
The concept of superposition theorem states that:
- A) The total response in a linear circuit is the algebraic sum of the responses due to each source acting independently
- B) The total voltage in a circuit is the sum of all individual voltages
- C) The power in the circuit is the product of voltage and current
- D) The total current is the sum of all individual currents
  Answer: A
The maximum power transfer theorem is applicable to:
- A) Only resistive loads
- B) Circuits with capacitors and inductors only
- C) Circuits with reactive components
- D) Any load regardless of its nature
  Answer: A

3. Alternating Current Fundamentals (continued)

The average value of an AC current over a complete cycle is:
- A) Zero
- B) Equal to its peak value
- C) Equal to its RMS value
- D) Half of its peak value
  Answer: A
The RMS value of an AC current is defined as:
- A) The value of DC current that would produce the same heating effect in a resistor
- B) The peak value divided by 2
- C) The average value over a period
- D) The value of the peak current multiplied by √2
  Answer: A
In a three-phase system, the line voltage is:
- A) Equal to the phase voltage
- B) √3 times the phase voltage
- C) Half the phase voltage
- D) Double the phase voltage
  Answer: B

4. Semiconductor Devices

In a BJT transistor, the region where the base-emitter junction is forward biased and the base-collector junction is reverse biased is called:
- A) Cutoff region
- B) Saturation region
- C) Active region
- D) Breakdown region
  Answer: C
Which type of MOSFET is known for having a lower threshold voltage compared to other types?
- A) N-channel MOSFET
- B) P-channel MOSFET
- C) Depletion-mode MOSFET
- D) Enhancement-mode MOSFET
  Answer: A
The primary function of a semiconductor diode is to:
- A) Amplify signals
- B) Switch electrical signals
- C) Rectify AC to DC
- D) Oscillate at high frequencies
  Answer: C

5. Signal Generators

An LC oscillator uses:
- A) A combination of resistors and capacitors
- B) A combination of inductors and capacitors
- C) A combination of transistors and resistors
- D) A combination of crystals and capacitors
  Answer: B
The main purpose of an oscillator circuit is to:
- A) Amplify signals
- B) Convert AC to DC
- C) Generate periodic waveforms
- D) Measure signal strength
  Answer: C

6. Amplifiers

The Class B amplifier operates in which mode?
- A) Both transistors conduct for the entire input cycle
- B) Only one transistor conducts for half of the input cycle
- C) Neither transistor conducts for any part of the cycle
- D) Both transistors conduct for a brief part of the cycle
  Answer: B
A Class AB amplifier is designed to combine:
- A) High efficiency with high linearity
- B) High efficiency with low distortion
- C) Low efficiency with high gain
- D) Low gain with low distortion
  Answer: A
The feedback in an amplifier can be:
- A) Positive or negative
- B) Linear or non-linear
- C) Voltage or current
- D) Active or passive
  Answer: A

General Questions Covering Multiple Topics

Which law states that the total current entering a junction equals the total current leaving the junction?
- A) Ohm's Law
- B) Kirchhoff’s Current Law
- C) Kirchhoff’s Voltage Law
- D) Superposition Theorem
  Answer: B
The phase difference between the current and voltage in a purely resistive AC circuit is:
- A) 0 degrees
- B) 90 degrees
- C) 180 degrees
- D) 60 degrees
  Answer: A
The characteristic of a semiconductor diode that allows current to flow only in one direction is:
- A) Rectification
- B) Amplification
- C) Switching
- D) Modulation
  Answer: A
An ideal op-amp has:
- A) Infinite input impedance and zero output impedance
- B) Zero input impedance and infinite output impedance
- C) Finite input and output impedance
- D) Zero input and output impedance
  Answer: A
In a series R-L circuit, the impedance at resonance is:
- A) Purely resistive
- B) Purely reactive
- C) Infinite
- D) Zero
  Answer: A
The primary application of a transformer-coupled amplifier is to:
- A) Provide impedance matching
- B) Filter out high-frequency noise
- C) Generate oscillations
- D) Rectify signals
  Answer: A
The function of a crystal oscillator in electronic circuits is to:
- A) Amplify weak signals
- B) Provide stable timing signals
- C) Rectify alternating current
- D) Filter out noise
  Answer: B
In a push-pull amplifier, the term "push-pull" refers to:
- A) The use of two transistors in series
- B) The use of two transistors in parallel
- C) The action of two transistors alternating between driving the load and providing feedback
- D) The combined action of two transistors driving the load alternately
  Answer: D

Part - 3

1. Basic Concept (continued)

The unit of electrical resistance is:
- A) Farad
- B) Henry
- C) Ohm
- D) Siemens
  Answer: C
The power dissipated by a resistor is given by:
- A) $P = V \times I$
- B) $P = V^2 / R$
- C) $P = I^2 \times R$
- D) All of the above
  Answer: D
In a circuit with resistors in series, the total resistance is:
- A) The sum of the individual resistances
- B) The product of the individual resistances
- C) The average of the individual resistances
- D) The reciprocal of the sum of the reciprocals of the individual resistances
  Answer: A
When resistors are connected in parallel, the total resistance is:
- A) The sum of the individual resistances
- B) The product of the individual resistances divided by the sum
- C) The average of the individual resistances
- D) The reciprocal of the sum of the reciprocals of the individual resistances
  Answer: D
In a resistive circuit, the voltage and current are:
- A) In phase
- B) Out of phase by 90 degrees
- C) Out of phase by 180 degrees
- D) Randomly phased
  Answer: A

2. Network Theorems (continued)

The purpose of Thevenin's theorem is to:
- A) Simplify complex linear circuits into a simple equivalent circuit
- B) Calculate the total current in a parallel circuit
- C) Measure the voltage drop across a resistor
- D) Determine the impedance of a circuit
  Answer: A
In an R-C circuit, the capacitive reactance is inversely proportional to:
- A) The resistance
- B) The frequency
- C) The capacitance
- D) The power factor
  Answer: B
In a series R-L circuit, the impedance is:
- A) The sum of the resistance and inductive reactance
- B) The product of the resistance and inductive reactance
- C) The difference between the resistance and inductive reactance
- D) The square root of the sum of the squares of the resistance and inductive reactance
  Answer: D
The maximum power transfer theorem applies to:
- A) Reactive components only
- B) Purely resistive circuits only
- C) Both resistive and reactive circuits
- D) AC circuits with multiple sources
  Answer: B
The Thevenin equivalent voltage is calculated by:
- A) Open circuit voltage across the terminals
- B) Short circuit current across the terminals
- C) Voltage drop across a known resistor
- D) Current through a known resistor
  Answer: A

3. Alternating Current Fundamentals (continued)

The formula for the average value of a sinusoidal wave is:
- A) $V_{\text{avg}} = \frac{2V_{\text{peak}}}{\pi}$
- B) $V_{\text{avg}} = \frac{V_{\text{peak}}}{2}$
- C) $V_{\text{avg}} = \frac{V_{\text{peak}}}{\sqrt{2}}$
- D) $V_{\text{avg}} = \frac{V_{\text{peak}} \times \pi}{2}$
  Answer: A
The phase relationship between the current and voltage in a capacitor is:
- A) Current leads voltage by 90 degrees
- B) Voltage leads current by 90 degrees
- C) Current and voltage are in phase
- D) Voltage leads current by 45 degrees
  Answer: A
In a three-phase system, the power factor is:
- A) The same as in a single-phase system
- B) Always unity
- C) Dependent on the phase angle between current and voltage
- D) Independent of load
  Answer: C
The primary purpose of a transformer is to:
- A) Increase or decrease voltage levels
- B) Convert AC to DC
- C) Amplify electrical signals
- D) Filter out high-frequency signals
  Answer: A
In a sinusoidal AC waveform, the time period is:
- A) The reciprocal of the frequency
- B) The product of the frequency and amplitude
- C) The average value of the waveform
- D) The maximum value of the waveform
  Answer: A

4. Semiconductor Devices

In a P-N junction diode, the region where no current flows is known as:
- A) Forward bias region
- B) Reverse bias region
- C) Depletion region
- D) Active region
  Answer: C
The primary difference between MOSFET and BJT is:
- A) MOSFET is current-controlled while BJT is voltage-controlled
- B) BJT is current-controlled while MOSFET is voltage-controlled
- C) Both are current-controlled devices
- D) Both are voltage-controlled devices
  Answer: B
The region of operation where a transistor is used as a switch is called:
- A) Active region
- B) Cutoff region
- C) Saturation region
- D) Breakdown region
  Answer: B
A Zener diode is typically used for:
- A) Rectification
- B) Voltage regulation
- C) Amplification
- D) Switching
  Answer: B
Which of the following semiconductor devices is known for high-speed switching applications?
- A) Diode
- B) BJT
- C) MOSFET
- D) SCR
  Answer: C

5. Signal Generators

An RC oscillator generates:
- A) Square waves
- B) Triangle waves
- C) Sinusoidal waves
- D) Sawtooth waves
  Answer: C
A waveform generator is used to:
- A) Filter signals
- B) Generate repetitive waveforms
- C) Rectify AC signals
- D) Amplify signals
  Answer: B
The main characteristic of a crystal oscillator is its:
- A) High frequency stability
- B) Low power consumption
- C) High gain
- D) Low noise
  Answer: A
An oscillator circuit can be classified as:
- A) LC, RC, and crystal oscillators
- B) Analog and digital oscillators
- C) Linear and non-linear oscillators
- D) High-frequency and low-frequency oscillators
  Answer: A
In an oscillator, the feedback network is used to:
- A) Provide power to the circuit
- B) Generate a stable reference voltage
- C) Control the frequency of oscillation
- D) Amplify the signal
  Answer: C

6. Amplifiers (continued)

The main advantage of a Class A amplifier is:
- A) High efficiency
- B) High linearity
- C) Low distortion
- D) High power output
  Answer: B
The Class C amplifier is typically used in:
- A) Audio amplifiers
- B) RF transmitters
- C) Low-frequency applications
- D) Linear amplifiers
  Answer: B
The gain of an amplifier can be increased by:
- A) Increasing the feedback
- B) Increasing the input signal
- C) Increasing the number of stages
- D) Decreasing the load resistance
  Answer: C
The main purpose of biasing in an amplifier is to:
- A) Improve efficiency
- B) Stabilize the operating point
- C) Increase the gain
- D) Decrease distortion
  Answer: B
In a differential amplifier, the output is:
- A) The average of the two input signals
- B) The sum of the two input signals
- C) The difference between the two input signals
- D) The product of the two input signals
  Answer: C

Part - 4

General Questions Covering Multiple Topics

The unit of inductance is:
- A) Farad
- B) Henry
- C) Ohm
- D) Watt
  Answer: B
The effective value of a waveform that varies with time is known as:
- A) Peak value
- B) Average value
- C) RMS value
- D) Peak-to-peak value
  Answer: C
The principle of superposition is used to:
- A) Analyze complex circuits with multiple sources
- B) Calculate total impedance in series circuits
- C) Determine the average value of AC signals
- D) Find the maximum power dissipation in a resistor
  Answer: A
The term "active component" refers to components that:
- A) Can amplify signals
- B) Can only pass signals
- C) Do not require external power
- D) Only consume power
  Answer: A
The efficiency of an amplifier is defined as:
- A) The ratio of output power to input power
- B) The ratio of input power to output power
- C) The ratio of voltage to current
- D) The ratio of resistance to reactance
  Answer: A
In a circuit, the power factor is:
- A) The ratio of real power to apparent power
- B) The ratio of reactive power to real power
- C) The ratio of voltage to current
- D) The ratio of impedance to resistance
  Answer: A
An operational amplifier (op-amp) with high input impedance and low output impedance is suitable for:
- A) Voltage follower circuits
- B) High-frequency oscillators
- C) Current amplification
- D) Power supply regulation
  Answer: A
In a sinusoidal waveform, the peak-to-peak value is:
- A) Twice the amplitude
- B) The same as the RMS value
- C) Half the amplitude
- D) The average value over a cycle
  Answer: A
The primary characteristic of an ideal voltage source is:
- A) Infinite internal resistance
- B) Zero internal resistance
- C) Infinite voltage
- D) Zero voltage
  Answer: B
In an AC circuit, the total impedance is:
- A) The sum of resistance and reactance
- B) The square root of the sum of the squares of resistance and reactance
- C) The difference between resistance and reactance
- D) The reciprocal of the sum of the reciprocals of resistance and reactance
  Answer: B
A transformer with a turns ratio of 1:2 will:
- A) Double the voltage and halve the current
- B) Halve the voltage and double the current
- C) Have no effect on the voltage or current
- D) Double both voltage and current
  Answer: A
In an AC circuit with both resistive and reactive components, the total power is:
- A) Real power only
- B) Reactive power only
- C) The sum of real and reactive power
- D) The product of real and reactive power
  Answer: C
The purpose of a bypass capacitor in an amplifier circuit is to:
- A) Block high-frequency signals
- B) Improve frequency response
- C) Stabilize the operating point
- D) Reduce power consumption
  Answer: B
The characteristic impedance of a transmission line is determined by:
- A) The resistance of the conductors
- B) The length of the transmission line
- C) The capacitance and inductance per unit length
- D) The operating frequency of the signal
  Answer: C
The primary use of a low-pass filter is to:
- A) Pass high-frequency signals and block low-frequency signals
- B) Pass low-frequency signals and block high-frequency signals
- C) Pass all signals without attenuation
- D) Block all signals without attenuation
  Answer: B
The gain-bandwidth product of an operational amplifier is:
- A) Constant for a given op-amp
- B) Variable depending on the feedback network
- C) The ratio of input impedance to output impedance
- D) The product of input voltage and output current
  Answer: A
In a rectifier circuit, the primary purpose of a filter capacitor is to:
- A) Smooth out the rectified output
- B) Increase the efficiency of rectification
- C) Reduce the ripple in the AC signal
- D) Provide a stable reference voltage
  Answer: A
The primary function of a transistor in a switching circuit is to:
- A) Amplify signals
- B) Control the flow of current
- C) Generate high-frequency signals
- D) Rectify AC signals
  Answer: B
The frequency response of an amplifier is:
- A) The range of frequencies over which the amplifier can operate effectively
- B) The range of voltages the amplifier can handle
- C) The range of temperatures the amplifier can tolerate
- D) The range of currents the amplifier can handle
  Answer: A
In a feedback amplifier circuit, the purpose of negative feedback is to: - A) Increase the gain of the amplifier - B) Reduce the gain and improve stability - C) Change the operating frequency - D) Increase the output impedance
Answer: B

NEC License Exam Guide

Search This Blog