12 Questions
What type of current periodically reverses direction and changes its magnitude continuously with time?
Alternating current (AC)
What is the usual waveform of alternating current in most electric power circuits?
Sine wave
What is the number of cycles or periods per second known as in alternating current?
Frequency
What is a single-phase power?
A two-wire power circuit
What are the components of AC power used for domestic and commercial applications?
Sine waves and square waves
Which wire is typically present in a single-phase power circuit, along with the phase wire?
Neutral wire
What is the advantage of a three-phase system compared to an equivalent single-phase system?
It transmits 73 percent more power using only 50 percent more wire
Why is electrical energy distributed as alternating current (AC)?
It allows power to be transmitted efficiently at high voltage
What is the formula to describe the power losses in the wire?
$P = I^2 * R$
What are the advantages of three-phase motors and transformers compared to single-phase ones?
150 percent greater horsepower and kilovolt-ampere rating
Why is the power delivered by a three-phase system relatively constant at all times?
Even though the power in each phase is pulsating, the total power at any instant will be relatively constant
Why is AC voltage used for transmission of electrical energy?
It allows efficient transmission at high voltage, reducing energy lost as heat due to resistance
This quiz provides a detailed explanation of alternating current (AC), single-phase and three-phase systems, and their components. It covers topics such as the waveform, frequency, and components of AC, as well as the differences between single-phase and three-phase systems.
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