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Alternating Current (AC) and Single-Phase vs Three-Phase Systems

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Alternating Current (AC) and Single-Phase vs Three-Phase Systems

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Questions and Answers

What type of current periodically reverses direction and changes its magnitude continuously with time?

Triangular current
Direct current (DC)
Square current
Alternating current (AC) (correct)

What is the usual waveform of alternating current in most electric power circuits?

Sawtooth wave
Square wave
Sine wave (correct)
Triangular wave

What is the number of cycles or periods per second known as in alternating current?

Amplitude
Frequency (correct)
Wavelength
Voltage

What is a single-phase power?

A two-wire power circuit (B) Signup and view all the answers

What are the components of AC power used for domestic and commercial applications?

Sine waves and square waves (D) Signup and view all the answers

Which wire is typically present in a single-phase power circuit, along with the phase wire?

Neutral wire (A) Signup and view all the answers

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 (C) Signup and view all the answers

Why is electrical energy distributed as alternating current (AC)?

It allows power to be transmitted efficiently at high voltage (C) Signup and view all the answers

What is the formula to describe the power losses in the wire?

$P = I^2 * R$ (C) Signup and view all the answers

What are the advantages of three-phase motors and transformers compared to single-phase ones?

150 percent greater horsepower and kilovolt-ampere rating (D) Signup and view all the answers

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 (C) Signup and view all the answers

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 (B) Signup and view all the answers