CET AC Circuit Analysis & Power 3

Question 1

The skin effect in AC conductors causes current to concentrate at the:

Accepted Answer

Outer surface of the conductor

Answer

The skin effect forces AC current toward the outer surface of a conductor, increasing effective resistance at higher frequencies.

Question 2

In a parallel RLC circuit, what condition defines resonance?

Accepted Answer

Susceptances cancel and total current is minimum

Answer

At parallel resonance, inductive and capacitive susceptances cancel, minimizing total current and maximizing impedance.

Question 3

What is the RMS value of a sine wave with a peak voltage of 170 V?

Accepted Answer

120.2 V

Answer

VRMS = Vpeak / √2 = 170 / 1.414 ≈ 120.2 V.

Question 4

Power factor correction in industrial facilities is most commonly achieved by adding:

Accepted Answer

Capacitor banks in parallel with inductive loads

Answer

Capacitor banks supply leading reactive power that cancels the lagging reactive power of inductive loads, improving power factor.

Question 5

In an AC circuit, complex power S is expressed as:

Accepted Answer

S = P + jQ

Answer

Complex power S = P + jQ, where P is real (true) power in watts and Q is reactive power in VAR.

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