Electrical Systems MCQs January 8, 2026August 23, 2024 by u930973931_answers 20 min Score: 0 Attempted: 0/20 Subscribe 1. What is the unit of electrical resistance? (A) Volt (B) Ampere (C) Ohm (D) Watt 2. Ohm’s Law relates which three electrical quantities? (A) Voltage, Current, and Resistance (B) Voltage, Current, and Power (C) Current, Power, and Resistance (D) Voltage, Power, and Capacitance 3. What is the unit of electrical power? (A) Volt (B) Watt (C) Ohm (D) Ampere 4. In a series circuit, how is the total resistance calculated? (A) Product of all resistances (B) Sum of all resistances (C) Reciprocal of the sum of reciprocals (D) Reciprocal of the product of all resistances 5. What is the purpose of a transformer? (A) To convert AC to DC (B) To store electrical energy (C) To step up or step down voltage (D) To regulate current flow 6. Which of the following devices stores electrical energy in an electric field? (A) Inductor (B) Transformer (C) Capacitor (D) Resistor 7. What is the unit of capacitance? (A) Coulomb (B) Henry (C) Ohm (D) Farad 8. Which component opposes changes in current flow? (A) Resistor (B) Inductor (C) Capacitor (D) Transformer 9. In AC circuits, what does the term “reactance” refer to? (A) Resistance to alternating current (B) Opposition due to capacitance and inductance (C) Total opposition to current flow (D) Measure of power dissipation 10. The power factor of an AC circuit is defined as: (A) The ratio of apparent power to real power (B) The ratio of reactive power to real power (C) The ratio of real power to apparent power (D) The ratio of voltage to current 11. What type of circuit is used to convert AC to DC? (A) Oscillator (B) Inverter (C) Transformer (D) Rectifier 12. In a parallel circuit, how is the total resistance calculated? (A) Reciprocal of the sum of reciprocals (B) Sum of all resistances (C) Product of all resistances (D) Average of all resistances 13. What is the primary function of a diode? (A) To allow current flow in both directions (B) To prevent current flow (C) To store electrical energy (D) To allow current flow in only one direction 14. Which device is used to measure electrical current? (A) Voltmeter (B) Ammeter (C) Ohmmeter (D) Wattmeter 15. What does the term “short circuit” refer to? (A) A complete path for current with very low resistance (B) A circuit with high resistance (C) A circuit with no current flow (D) A break in the circuit path 16. Which component protects circuits from overcurrent? (A) Capacitor (B) Fuse (C) Inductor (D) Diode 17. What is the function of a relay? (A) To switch or control a circuit remotely (B) To amplify signals (C) To store energy (D) To convert AC to DC 18. What does an oscilloscope measure? (A) Voltage only (B) Current only (C) Resistance (D) Voltage as a function of time 19. In a three-phase system, what is the phase difference between phases? (A) 120° (B) 90° (C) 60° (D) 180° 20. What is the function of a circuit breaker? (A) To increase voltage (B) To measure current (C) To protect the circuit from overloads or short circuits (D) To rectify AC to DC