AC Circuit Analysis: Master the Fundamentals of AC Circuits

Question 1

Which of the following is NOT a unit of power factor?

Accepted Answer

Watts

Answer

Per unit

Answer

Percentage

Answer

Lagging or Leading

Question 2

The average power consumed by a purely inductive circuit is:

Accepted Answer

Zero

Answer

Equal to the apparent power

Answer

Equal to the reactive power

Answer

Dependent on the circuit parameters

Question 3

In an AC circuit, a phase shift can be caused by:

Accepted Answer

Both inductors and capacitors

Answer

Inductors

Answer

Capacitors

Answer

Resistors

Question 4

Select the method commonly used to improve the power factor of an inductive circuit:

Accepted Answer

Adding a capacitor in parallel

Answer

Adding a resistor in parallel

Answer

Increasing the frequency

Answer

Decreasing the inductance

Question 5

Identify the primary function of a transformer:

Accepted Answer

Changes the voltage of an AC signal

Answer

Converts AC to DC

Answer

Converts DC to AC

Answer

Stores electrical energy

Question 6

Select the equation for the voltage across an inductor:

Accepted Answer

VL = ILωL

Answer

VL = IL / ωC

Answer

VL = ILR

Answer

VL = ILjωC

Question 7

Identify the unit of impedance:

Accepted Answer

Ohm

Answer

Henry

Answer

Farad

Answer

Siemens

Question 8

Which of the following accurately measures the ratio of actual power used in a circuit to its apparent power?

Accepted Answer

Power factor

Answer

Actual power

Answer

Apparent power

Answer

Phase difference

Question 9

Which of these factors does NOT influence the power factor of an AC circuit?

Accepted Answer

Voltage

Answer

Resistance

Answer

Inductance

Answer

Capacitance

Question 10

When an inductor is connected in series with a resistor in an AC circuit, the circuit becomes:

Accepted Answer

Inductive

Answer

Capacitive

Answer

Resistive

Answer

Resonant

Question 11

The impedance of an AC circuit is defined as the:

Accepted Answer

Ratio of voltage phasor to current phasor

Answer

Product of resistance and inductance

Answer

Difference between resistance and capacitance

Answer

Sum of resistance and inductance

Question 12

The power factor of an AC circuit is:

Accepted Answer

Cosine of the phase angle between voltage and current phasors

Answer

Tangent of the phase angle between voltage and current phasors

Answer

Sine of the phase angle between voltage and current phasors

Question 13

The skin effect in AC circuits refers to:

Accepted Answer

Current density being concentrated near the surface of a conductor at high frequencies

Answer

Increased resistance of a conductor at high frequencies

Answer

Capacitive effects becoming dominant at high frequencies

Question 14

In AC circuits, impedance is commonly measured in which unit?

Accepted Answer

Ohm

Answer

Farad

Answer

Watt

Answer

Henry

Question 15

In a sinusoidal waveform represented by v(t) = Vm sin(ωt + φ), which parameter determines the maximum amplitude of the waveform?

Accepted Answer

Vm

Answer

ω

Answer

t

Answer

φ

Question 16

In a purely inductive AC circuit, the phase relationship between current and voltage is characterized by:

Accepted Answer

Current lags behind voltage by 90°

Answer

Current leads voltage by 90°

Answer

Current is in phase with voltage

Answer

Phase relationship depends on specific values of inductance and frequency

Question 17

Which of the following correctly defines the power factor of an AC circuit?

Accepted Answer

Cosine of the phase angle between voltage and current

Answer

Sine of the phase angle between voltage and current

Answer

Cotangent of the phase angle between voltage and current

Answer

Tangent of the phase angle between voltage and current

Question 18

In AC circuits, which component stores energy primarily in the form of a magnetic field?

Accepted Answer

Inductor

Answer

Resistor

Answer

Capacitor

Answer

Diode

Question 19

A step-up transformer has a turns ratio of 2:1. If the primary voltage is 240 V, what is the secondary voltage?

Accepted Answer

480 V

Answer

30 V

Answer

180 V

Answer

120 V

Question 20

In an AC circuit containing a capacitor, the phase relationship between current and voltage is characterized by:

Accepted Answer

Current leads voltage by 90°

Answer

Current lags voltage by 90°

Answer

Phase relationship depends on specific values of capacitance and frequency

Answer

Current is in phase with voltage

Question 21

Which measuring device is specifically designed to measure the power consumed by an AC circuit?

Accepted Answer

Wattmeter

Answer

Voltmeter

Answer

Multimeter

Answer

Ammeter

Question 22

In an AC circuit with a series connection of a resistor, capacitor, and inductor, the total impedance is given by:

Accepted Answer

Square root of (R² + (XL - XC)²)

Answer

Cannot be determined without specific values of R, XL, and XC

Answer

R + XL + XC

Answer

(R² + XL² + XC²) / (R + XL + XC)

Question 23

In an AC circuit, resonance occurs at the frequency where:

Accepted Answer

Inductive reactance equals capacitive reactance

Answer

Circuit current is minimum

Answer

Circuit power factor is unity

Answer

Circuit impedance is maximum