CEP Electrical Theory & Principles 3

Question 1

Which of the following best describes impedance in an AC circuit?

Accepted Answer

The total opposition to AC current flow combining resistance and reactance

Answer

Impedance (Z) is the complex combination of resistance (R) and reactance (X), expressed in ohms: Z = √(R² + X²).

Question 2

In a three-phase balanced system, the phase voltage is related to the line voltage by:

Accepted Answer

V_line = V_phase × √3

Answer

In a balanced three-phase wye (star) system, the line voltage equals the phase voltage multiplied by √3 (≈1.732).

Question 3

The energy stored in a capacitor is expressed as:

Accepted Answer

E = ½CV²

Answer

The energy stored in a capacitor is E = ½CV², where C is capacitance in farads and V is voltage in volts.

Question 4

What happens to the total capacitance when capacitors are connected in series?

Accepted Answer

Total capacitance decreases below the smallest value

Answer

Series capacitors follow the reciprocal rule (1/CT = 1/C1 + 1/C2 + ...), resulting in a total less than the smallest capacitor.

Question 5

In an AC circuit, resonance occurs when:

Accepted Answer

Inductive reactance equals capacitive reactance

Answer

Resonance occurs when XL = XC, causing them to cancel, leaving only resistance to limit current, and power factor reaches unity.

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