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Question 1: What is the SI unit of electrical resistance? A. Volt B. Ohm C. Ampere D. Coulomb Correct: B Explanation: Electrical resistance is measured in ohms (Ω), defined by Ohm’s law as the ratio of voltage to current (R = V/I). Question 2: Who is considered the “father of electrical engineering”? A. Nikola Tesla B. Thomas Edison C. James Clerk Maxwell D. Michael Faraday Correct: C Explanation: Maxwell unified electricity and magnetism into a single theory (Maxwell’s equations), laying the foundation for modern electrical engineering.
Question 3: Which branch of electrical engineering deals primarily with signal processing? A. Power systems B. Control systems C. Electronics D. Telecommunications Correct: D Explanation: Telecommunications engineering focuses on the transmission and processing of information-carrying signals over distances. Question 4: Ohm’s law expresses the relationship between voltage (V), current (I), and resistance (R) as: A. V = I × R B. I = V / R² C. R = V / I² D. V = I / R Correct: A Explanation: Ohm’s law states that voltage across a conductor is directly
Explanation: In resistive circuits, P can be expressed as IV, V²/R, or I²R depending on known quantities. Question 7: What does a capacitor store in an electrical circuit? A. Electric charge B. Magnetic flux C. Electric current D. Electromotive force Correct: A Explanation: A capacitor stores energy in the electric field between its plates by accumulating charge. Question 8: What is the reactance of a capacitor (X ₙ ) at frequency f? A. 2πfC B. 1 / (2πfC) C. 2πfL D. f / (2πL) Correct: B Explanation: Capacitive reactance Xc = 1/(2πfC), inversely proportional to frequency and capacitance.
Question 9: Kirchhoff’s Voltage Law (KVL) states that: A. Sum of currents at a node equals zero B. Sum of voltages around any closed loop equals zero C. Power in must equal power out D. Voltage divides in proportion to resistance Correct: B Explanation: KVL is based on energy conservation around a closed electrical loop: the algebraic sum of potential differences is zero. Question 10: Kirchhoff’s Current Law (KCL) is derived from the conservation of: A. Energy B. Momentum C. Charge D. Power Correct: C Explanation: KCL states that the algebraic sum of currents entering a node equals the sum leaving, reflecting charge conservation.
Question 13: Thevenin’s theorem allows any linear two-terminal circuit to be replaced by: A. A single current source and resistor in series B. A single voltage source and resistor in series C. A single voltage source and resistor in parallel D. A single current source and resistor in parallel Correct: B Explanation: Thevenin’s theorem simplifies analysis by replacing complex networks with a voltage source and series resistance. Question 14: In an AC circuit, the term “impedance” refers to: A. Resistance only B. Reactance only C. Vector sum of resistance and reactance D. Reciprocal of admittance Correct: C Explanation: Impedance (Z) combines resistance (R) and reactance (X) vectorially: Z = R + jX.
Question 15: The RMS (root-mean-square) value of a sinusoidal current is: A. Iₚₑₐₖ / 2 B. Iₚₑₐₖ / √ 2 C. √ 2 × Iₚₑₐₖ D. 2 × Iₚₑₐₖ Correct: B Explanation: RMS value for sine wave is peak value divided by √2, representing equivalent DC value for power calculations. Question 16: Which device converts electrical energy into mechanical energy? A. Transformer B. Motor C. Generator D. Rectifier Correct: B Explanation: Electric motors convert electrical power into mechanical rotation via electromagnetic interaction.
B. Field-Effect Transistor (FET) C. Thyristor D. Zener diode Correct: B Explanation: FETs operate via an electric field controlling a channel of majority carriers; BJTs use both electrons and holes. Question 20: Thyristors are best described as: A. Voltage-controlled switches B. Current-controlled switches C. Unidirectional switches triggered by gate D. Bidirectional AC switches Correct: C Explanation: A thyristor latches on when a gate pulse is applied in forward bias and remains on until current falls below holding level. Question 21: What is the purpose of a circuit breaker? A. To step down voltage B. To limit current continuously C. To interrupt fault currents automatically
D. To convert AC to DC Correct: C Explanation: Circuit breakers protect circuits by interrupting excessive current during overloads or short circuits. Question 22: Which law describes the force between two magnetic poles? A. Coulomb’s law B. Newton’s law C. Biot–Savart law D. Ampère’s force law Correct: A Explanation: Coulomb’s law for magnetism states that force between poles is proportional to the product of pole strengths and inversely to the square of distance. Question 23: Maxwell’s addition to Ampère’s law introduced: A. Displacement current B. Magnetic monopoles C. Eddy currents
D. 3 × Phase voltage Correct: C Explanation: In a Y-connection, line voltage VL = √3 × Vphase. Question 26: Which quantity represents the opposition to change in current in an inductor? A. Resistance B. Capacitance C. Inductance D. Reactance Correct: D Explanation: Inductive reactance XL = 2πfL opposes AC current change, proportional to frequency and inductance. Question 27: In nodal analysis, unknowns are: A. Loop currents B. Branch currents C. Node voltages D. Source impedances Correct: C
Explanation: Nodal analysis solves circuit equations using voltages at nodes relative to a reference node. Question 28: Which theorem states that the response in any element is the sum of responses caused by each independent source acting alone? A. Superposition theorem B. Reciprocity theorem C. Millman’s theorem D. Thevenin’s theorem Correct: A Explanation: Superposition applies only to linear circuits, allowing analysis by considering one source at a time. Question 29: Millman’s theorem simplifies analysis of parallel branches containing: A. Current sources only B. Voltage sources only C. Both current and voltage sources with resistances D. Reactive elements only
Explanation: Q = (reactive energy stored)/(energy dissipated per cycle), indicating selectivity. Question 32: Power factor in AC circuits is defined as: A. I × V B. cos ϕ C. tan ϕ D. sin ϕ Correct: B Explanation: Power factor is the cosine of the phase angle between voltage and current, representing real power fraction. Question 33: Which device improves power factor in industrial loads? A. Inductor banks B. Capacitor banks C. Resistor banks D. Transformer tap changer Correct: B Explanation: Capacitors supply leading reactive current, offsetting inductive load lag and improving power factor.
Question 34: What is the main function of a diode bridge? A. Voltage regulation B. AC to DC conversion C. Frequency multiplication D. Impedance matching Correct: B Explanation: A bridge rectifier uses four diodes to produce full-wave DC output from AC input. Question 35: Which type of transformer has a single winding acting as both primary and secondary? A. Autotransformer B. Isolation transformer C. Step-down transformer D. Three-phase transformer Correct: A Explanation: An autotransformer shares windings, providing voltage adjustment with reduced size and cost.
A. Zener diode B. Tunnel diode C. Schottky diode D. Photodiode Correct: A Explanation: A Zener diode maintains nearly constant voltage over a specified current range when reverse-biased beyond its breakdown. Question 39: What is meant by “electromagnetic induction”? A. Generating heat in a conductor B. Inducing current by changing magnetic flux C. Converting DC to AC D. Inducing voltage by applying current Correct: B Explanation: Faraday’s law states that a changing magnetic flux through a coil induces an electromotive force (EMF). Question 40: Which instrument measures current without direct electrical connection? A. Voltmeter
B. Ammeter C. Clamp meter D. Oscilloscope Correct: C Explanation: Clamp meters sense magnetic field around a conductor to measure current noninvasively. Question 41: What is the time constant τ in an RC circuit? A. R × L B. L / R C. R × C D. 1 / (R × C) Correct: C Explanation: In an RC circuit, τ = R C determines the exponential charging/discharging rate of the capacitor. Question 42: Transient analysis in an RL circuit focuses on current change due to: A. Capacitance B. Inductance
