Free Bachelor of Electrical Engineering Basic Electrical Questions and Answers — Questions and Answers

Question 1: In an AC circuit, which of the following accurately depicts the average value?

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

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 2: Who developed an approach to measure current and defined electric current?

Alessandro Antonio Volta
Nikola Tesla
Andre-Marie Ampere (Correct answer)
Michael Faraday

Correct answer: Andre-Marie Ampere

André-Marie Ampère was a pioneering French physicist and mathematician who made fundamental contributions to the understanding of electromagnetism. He developed the theory of electrodynamics and formulated Ampère's law, which describes the relationship between electric current and the magnetic field it produces. The unit of electric current, the ampere, is named in his honor.

Question 3: How many electrons are required to produce a 2 Coulomb electric charge?

3.204 * 1019 electrons
6.24 * 1018 electrons
12.48 * 1018 electrons (Correct answer)
1.602 * 1019 electrons

Correct answer: 12.48 * 1018 electrons

The charge of a single electron is approximately 1.602 x 10^-19 Coulombs. To determine the number of electrons required to produce a 2 Coulomb electric charge, you divide the total charge by the charge of one electron. Calculation: 2 C / (1.602 x 10^-19 C/electron) ≈ 1.248 x 10^19 electrons, which can also be written as 12.48 x 10^18 electrons.

Question 4: Which of the following statements regarding direct current is true?

Flows in one direction
Magnitude is constant
Frequency is zero
Can be transported to larger distances with less loss in power (Correct answer)

Correct answer: Can be transported to larger distances with less loss in power

While conventional DC transmission has higher losses over long distances compared to AC, High-Voltage Direct Current (HVDC) transmission systems are specifically designed to transport power over very long distances with significantly less loss than equivalent AC systems. HVDC is particularly advantageous for submarine cables and long-haul overhead lines, making this statement true in the context of modern power transmission technologies.

Question 5: Who was the first person to experience the power of magnetism?

Gustav Robert Kirchhoff
Hans Christian Orsted (Correct answer)
Alexander Graham Bell
Michael Faraday

Correct answer: Hans Christian Orsted

Hans Christian Ørsted, a Danish physicist, made the groundbreaking discovery in 1820 that electric currents produce magnetic fields. He observed that a compass needle deflected when placed near a wire carrying an electric current, demonstrating the fundamental connection between electricity and magnetism and laying the foundation for electromagnetism.

Question 6: Which of the following statements regarding electrical conductivity is true? Which of the following statements regarding electrical conductivity is true?

It is the product of current density and electric field
It is the ratio of current density to the electric field (Correct answer)
It is the reciprocal of the product of current density and electric field
It is the ratio of the electric field to current density

Correct answer: It is the ratio of current density to the electric field

Electrical conductivity (σ) is a material property that quantifies its ability to conduct electric current. It is defined as the ratio of the current density (J), which is the current per unit cross-sectional area, to the electric field (E) that drives the current. This relationship is expressed by the equation J = σE, a microscopic form of Ohm's Law.

Question 7: What is the cause of the current's flow?

Nucleus
Protons
Protons and Electrons
Electrons (Correct answer)

Correct answer: Electrons

Electric current is fundamentally the flow of electric charge. In most common conductors, such as metals, the charge carriers are free electrons. These electrons are not tightly bound to individual atoms and can move freely through the material under the influence of an electric field, thus constituting the electric current.

Question 8: Which of the following must be zero according to KCL?

Algebraic sum of voltages across the input and output
Algebraic sum of currents in closed-loop
Algebraic sum of power in closed-loop
Algebraic sum of currents entering and leaving a junction (Correct answer)

Correct answer: Algebraic sum of currents entering and leaving a junction

Kirchhoff's Current Law (KCL) is a fundamental principle in circuit analysis, stating that the algebraic sum of all currents entering and leaving any junction (or node) in an electrical circuit must be zero. This law is a direct application of the principle of conservation of electric charge, meaning that charge cannot accumulate at a node.

Question 9: How many possible directions may the electric field have at one location?

Two
Zero
One (Correct answer)
Many

Correct answer: One

The electric field at any given location in space is a vector quantity, meaning it has both magnitude and a specific direction. For a particular point, the net electric field resulting from all surrounding charges will always point in a single, unique direction, indicating the force that a positive test charge would experience at that exact spot.

Question 10: When there are more secondary turns than main turns in a transformer, which of the following will happen?

The power gets stepped down
The voltage gets stepped down
The voltage gets stepped up (Correct answer)
The power gets stepped up

Correct answer: The voltage gets stepped up

In a transformer, the voltage transformation is directly proportional to the turns ratio. If the number of turns in the secondary winding is greater than the number of turns in the primary winding (Ns > Np), the transformer is designed to step up the voltage. This means the output voltage across the secondary coil will be higher than the input voltage across the primary coil.

Question 11: Which of the following statements regarding electrical engineering's voltage transformation ratio is true?

Ratio of power in primary to power in secondary
Ratio of secondary current to the primary current
Ratio of number of primary turns to the number of secondary turns
Ratio of induced emf in secondary to induced emf in primary (Correct answer)

Correct answer: Ratio of induced emf in secondary to induced emf in primary

The voltage transformation ratio (or turns ratio) of a transformer is defined as the ratio of the induced electromotive force (emf) in the secondary winding to the induced emf in the primary winding. This ratio is approximately equal to the ratio of the number of turns in the secondary coil to the number of turns in the primary coil, and it dictates how voltage is stepped up or down.

Question 12: Which of the following statements regarding the induced emf in the transformer primary is true according to electrical engineering fundamentals?

It is the product of secondary turns and emf induced per turn
It is the ratio of secondary turns to emf induced per turn
It is the ratio of primary turns to emf induced per turn
It is the product of primary turns and emf induced per turn (Correct answer)

Correct answer: It is the product of primary turns and emf induced per turn

The total induced electromotive force (emf) in the primary winding of a transformer is directly proportional to the number of turns in that winding. Each turn contributes an equal amount of induced emf. Therefore, the total primary induced emf is calculated by multiplying the number of primary turns by the emf induced per single turn.

Question 13: When the secondary is open, which of the following currents is drawn by the primary circuit of an ideal transformer?

Working on current
Magnetizing current (Correct answer)
Leakage current
Secondary current

Correct answer: Magnetizing current

When the secondary winding of an ideal transformer is open-circuited, no load current flows through it. However, the primary winding still draws a small current from the supply, known as the magnetizing current. This current is responsible for establishing and maintaining the alternating magnetic flux in the transformer's core, which is essential for its operation.

Question 14: What does an electrical element's positive power mean?

Element is supplying power
Element is absorbing power (Correct answer)
Element is neither absorbing nor supplying power
Element may absorb or supply power

Correct answer: Element is absorbing power

In electrical engineering, the convention for power is that a positive value indicates that an element is absorbing or consuming power from the circuit. Conversely, if an element is supplying or generating power, its power value would be considered negative. This convention helps in analyzing power flow within a circuit.

Question 15: How does the supply voltage affect a DC motor's response to an induce emf?

It will be half of the supply voltage
It will oppose the supply voltage (Correct answer)
It will be double the supply voltage
It will aid 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 16: Which of the following electrical engineering circuit types cannot be examined using Ohm's law?

Conductors
Linear
Bilateral
Unilateral (Correct answer)

Correct answer: Unilateral

Ohm's law describes a linear relationship between voltage and current (V=IR), implying a constant resistance regardless of current direction. Unilateral circuits, such as those containing diodes or transistors, exhibit non-linear and direction-dependent characteristics, meaning their V-I relationship cannot be accurately described by a single, constant resistance value as implied by Ohm's law. Therefore, Ohm's law is not universally applicable to unilateral circuits.

Free Bachelor of Electrical Engineering Basic Electrical Questions and Answers

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