Single Phase AC Circuits Question & AnswersJune 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 None Hint2). The power factor of an AC circuit can have a value between ______________________? 0 and 1 -1 and 1 -∞ and ∞ 0 and ∞ None Hint3). Which of the following devices is used to improve the power factor of an AC circuit? Transformer Capacitor Inductor Diode None Hint4). The unit of apparent power in an AC circuit is ____________________? Volt (V) Ampere (A) Watt (W) Volt-ampere (VA) None Hint5). The power factor of an inductive circuit is generally _____________________? Lagging Leading Unity Zero None Hint6). Who is credited with the invention of the single-phase AC induction motor? Nikola Tesla Thomas Edison Michael Faraday James Watt None Hint7). In which year was the first successful demonstration of a single-phase AC power system held? 1879 1885 1893 1901 None Hint8). Which type of generator is commonly used in single-phase AC systems? Synchronous generator Induction generator Direct current (DC) generator Solar generator None Hint9). What is the frequency of standard single-phase AC power in most countries? 50 Hz 60 Hz 25 Hz 100 Hz None Hint10). Who introduced the concept of a polyphase AC power system? Nikola Tesla Thomas Edison George Westinghouse Benjamin Franklin None Hint11). The transmission of electricity over long distances using AC power became feasible due to the invention of ______________________? Transformers Induction motors Power inverters Vacuum tubes None Hint12). 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 None Hint13). Who won the “War of Currents” by demonstrating the superiority of AC power over DC power? Nikola Tesla Thomas Edison George Westinghouse Samuel Morse None Hint14). 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 None Hint15). The adoption of single-phase AC power systems contributed to the electrification of which sector first? Residential Industrial Transportation Agricultural None HintSingle Phase AC Circuits MCQ for Interviews16). In a single-phase AC circuit, the current and voltage waveforms are out of phase by ______________________? 0 degrees 90 degrees 180 degrees 360 degrees None Hint17). A single-phase AC circuit with a purely resistive load will have a power factor of ________________________? 0 0.5 1 2 None Hint18). 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 None Hint19). Which component is used to measure the power in a single-phase AC circuit? Ammeter Voltmeter Wattmeter Multimeter None Hint20). 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 None Hint21). Which of the following quantities remains constant in a purely resistive single-phase AC circuit? Voltage Current Power Impedance None Hint22). In a single-phase AC circuit, the voltage and current vary with time in which pattern? Linearly Exponentially Sinusoidally Randomly None Hint23). 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 None Hint24). Which component in a single-phase AC circuit causes the power factor to lag? Resistor Inductor Capacitor Transformer None Hint25). Which of the following devices is used to measure the power factor in a single-phase AC circuit? Ammeter Voltmeter Power factor meter Oscilloscope None Hint26). 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 None Hint27). Which component is commonly used to protect other components from voltage spikes in a single-phase AC circuit? Resistor Capacitor Inductor Surge protector None Hint28). Which component is used to measure the flow of current in a single-phase AC circuit? Voltmeter Ammeter Ohmmeter Wattmeter None Hint29). Which component is used to measure the potential difference between two points in a single-phase AC circuit? Voltmeter Ammeter Ohmmeter Wattmeter None Hint30). Which component is commonly used to convert electrical energy into other forms of energy in a single-phase AC circuit? Resistor Capacitor Inductor Motor None HintSingle Phase AC Circuits MCQ for Quiz31). 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 None Hint32). Which device is commonly used to measure the RMS value of voltage or current in a single-phase AC circuit? Ammeter Voltmeter Multimeter Oscilloscope None Hint33). 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 None Hint34). 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 None Hint35). 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 None Hint36). 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 None Hint37). Which of the following is a disadvantage of single-phase AC induction motors? Simple construction Reduced maintenance requirements Lower starting torque Higher power factor None Hint38). Which type of single-phase AC circuit is used in most household electrical appliances? RLC circuit RL circuit RC circuit LC circuit None Hint39). What type of single-phase AC circuit is used in fluorescent lamps? RLC circuit RL circuit RC circuit LC circuit None HintRead 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 None HintFor More MCQsMagnetic Circuit Question & AnswersElectric Circuit Question & AnswersRLC Circuit Question & Answers Time's up
