Single Phase AC Circuits Question & Answers June 5, 2023 By Wat Electrical This article lists 40 Single Phase AC Circuits MCQs for engineering students. All the Single Phase AC Circuits Questions & Answers below include a hint and a link to the relevant topic wherever possible. This is helpful for users who are preparing for their exams, interviews, or professionals who would like to brush up on the fundamentals of the Single Phase AC Circuits. A single-phase AC circuit is an electrical circuit that operates using a single-phase alternating current (AC) power supply. In a single-phase AC circuit, the voltage and current vary sinusoidally over time. The power supply consists of a single sinusoidal voltage waveform. In most residential and small commercial applications, the standard single-phase AC power supply has a frequency of 50 or 60 Hertz (Hz). The voltage in a single-phase AC circuit follows a sinusoidal waveform, commonly referred to as a sine wave. The voltage rises to a maximum positive value, then decreases to zero, and finally reaches a maximum negative value before returning to zero. This cycle repeats itself continuously. It's important to note that while single-phase AC circuits are commonly used in residential and small commercial applications, three-phase AC circuits are typically employed in industrial and large-scale power distribution systems due to their higher power-carrying capacity and efficiency. 1). In a single-phase AC circuit, the power factor is defined as the ratio of _______________________? Active power to apparent power Active power to reactive power Reactive power to apparent power Reactive power to active power Hint 2). The power factor of an AC circuit can have a value between ______________________? 0 and 1 -1 and 1 -∞ and ∞ 0 and ∞ Hint 3). Which of the following devices is used to improve the power factor of an AC circuit? Transformer Capacitor Inductor Diode Hint 4). The unit of apparent power in an AC circuit is ____________________? Volt (V) Ampere (A) Watt (W) Volt-ampere (VA) Hint 5). The power factor of an inductive circuit is generally _____________________? Lagging Leading Unity Zero Hint 6). Who is credited with the invention of the single-phase AC induction motor? Nikola Tesla Thomas Edison Michael Faraday James Watt Hint 7). In which year was the first successful demonstration of a single-phase AC power system held? 1879 1885 1893 1901 Hint 8). Which type of generator is commonly used in single-phase AC systems? Synchronous generator Induction generator Direct current (DC) generator Solar generator Hint 9). What is the frequency of standard single-phase AC power in most countries? 50 Hz 60 Hz 25 Hz 100 Hz Hint 10). Who introduced the concept of a polyphase AC power system? Nikola Tesla Thomas Edison George Westinghouse Benjamin Franklin Hint 11). The transmission of electricity over long distances using AC power became feasible due to the invention of ______________________? Transformers Induction motors Power inverters Vacuum tubes Hint 12). The development of single-phase AC power systems played a significant role in the growth of which industry? Telecommunications Automotive Oil and gas Electric power distribution Hint 13). Who won the “War of Currents” by demonstrating the superiority of AC power over DC power? Nikola Tesla Thomas Edison George Westinghouse Samuel Morse Hint 14). Which famous experiment demonstrated the viability of AC power by transmitting it over long distances? Niagara Falls experiment Bell Jar experiment Franklin’s Kite experiment Voltaic Pile experiment Hint 15). The adoption of single-phase AC power systems contributed to the electrification of which sector first? Residential Industrial Transportation Agricultural Hint Single Phase AC Circuits MCQ for Interviews 16). In a single-phase AC circuit, the current and voltage waveforms are out of phase by ______________________? 0 degrees 90 degrees 180 degrees 360 degrees Hint 17). A single-phase AC circuit with a purely resistive load will have a power factor of ________________________? 0 0.5 1 2 Hint 18). In a single-phase AC circuit, if the voltage is given by V = 220V sin(ωt), the frequency of the AC supply is _________________? 50 Hz 60 Hz 100 Hz 120 Hz Hint 19). Which component is used to measure the power in a single-phase AC circuit? Ammeter Voltmeter Wattmeter Multimeter Hint 20). In a single-phase AC circuit, if the voltage lags behind the current, the load is most likely __________________? Purely resistive Purely inductive Purely capacitive A combination of inductive and capacitive Hint 21). Which of the following quantities remains constant in a purely resistive single-phase AC circuit? Voltage Current Power Impedance Hint 22). In a single-phase AC circuit, the voltage and current vary with time in which pattern? Linearly Exponentially Sinusoidally Randomly Hint 23). The peak value of an AC voltage waveform is 100 V. What is the RMS value of the waveform? 100 V 70.7 V 141.4 V 200 V Hint 24). Which component in a single-phase AC circuit causes the power factor to lag? Resistor Inductor Capacitor Transformer Hint 25). Which of the following devices is used to measure the power factor in a single-phase AC circuit? Ammeter Voltmeter Power factor meter Oscilloscope Hint 26). What is the function of a diode in a single-phase AC circuit? To convert AC to DC To regulate voltage To store energy To increase current flow Hint 27). Which component is commonly used to protect other components from voltage spikes in a single-phase AC circuit? Resistor Capacitor Inductor Surge protector Hint 28). Which component is used to measure the flow of current in a single-phase AC circuit? Voltmeter Ammeter Ohmmeter Wattmeter Hint 29). Which component is used to measure the potential difference between two points in a single-phase AC circuit? Voltmeter Ammeter Ohmmeter Wattmeter Hint 30). Which component is commonly used to convert electrical energy into other forms of energy in a single-phase AC circuit? Resistor Capacitor Inductor Motor Hint Single Phase AC Circuits MCQ for Quiz 31). The maximum value of voltage in a single-phase AC circuit is known as _____________________? Root Mean Square (RMS) value Average value Peak value Crest factor Answer Hint 32). Which device is commonly used to measure the RMS value of voltage or current in a single-phase AC circuit? Ammeter Voltmeter Multimeter Oscilloscope Hint 33). Which of the following is a disadvantage of single-phase AC circuits? Higher power transmission efficiency Limited power capacity Improved voltage stability Reduced line losses Hint 34). What is a major drawback of single-phase AC motors compared to three-phase AC motors? Lower efficiency Higher cost Limited torque output Larger physical size Hint 35). Which of the following is a disadvantage of single-phase AC power distribution systems? Simplified wiring and installation Lower electrical losses Reduced voltage fluctuations Unbalanced loading on the phases Hint 36). What is a limitation of single-phase AC welding compared to three-phase AC welding? Higher welding speed Smoother weld bead appearance Lower heat input Limited welding current capacity Hint 37). Which of the following is a disadvantage of single-phase AC induction motors? Simple construction Reduced maintenance requirements Lower starting torque Higher power factor Hint 38). Which type of single-phase AC circuit is used in most household electrical appliances? RLC circuit RL circuit RC circuit LC circuit Hint 39). What type of single-phase AC circuit is used in fluorescent lamps? RLC circuit RL circuit RC circuit LC circuit Hint Read more about RLC Circuit 40). In which type of single-phase AC circuit does the current waveform lead the voltage waveform? Inductive circuit Capacitive circuit Resistive circuit None of the above Hint For More MCQs Magnetic Circuit Question & Answers Electric Circuit Question & Answers RLC Circuit Question & Answers Time's up
