Master AC Circuits: Enhance Your Electrical Engineering Skills

Question 1

Which of the following components contributes to the inductive reactance of an AC circuit?

Accepted Answer

Inductors

Answer

Transformers

Question 2

A transformer is an AC circuit element that primarily:

Accepted Answer

Transfers electrical energy from one circuit to another

Answer

Blocks the flow of DC current

Question 3

In an AC circuit, the current:

Accepted Answer

Can either lag or lead the voltage depending on the circuit elements

Answer

Remains in phase with the voltage

Question 4

The RMS value of an AC voltage represents:

Accepted Answer

The value of the voltage that produces the same heating effect as an equivalent DC voltage

Answer

The average value of the voltage over one cycle

Question 5

Which of the following does NOT directly influence the impedance of an AC circuit?

Accepted Answer

Area of the capacitor plates

Answer

Frequency of the AC current

Answer

Resistance of the circuit

Answer

Inductance of the circuit

Question 6

In an AC circuit, how does impedance change when resistance increases while reactance remains constant?

Accepted Answer

Increases

Answer

Decreases

Answer

Stays the same

Answer

Cannot be determined

Question 7

Which statement about AC circuits is incorrect?

Accepted Answer

Power in an AC circuit is constant

Answer

Alternating current periodically changes direction

Answer

Alternating voltage periodically changes magnitude and direction

Answer

AC circuits can consist of resistors, capacitors, or inductors

Question 8

Which component exhibits the highest impedance at high frequencies in an AC circuit?

Accepted Answer

Inductor

Answer

Resistor

Answer

Capacitor

Answer

Diode

Question 9

A circuit with a lagging current has a power factor of:

Accepted Answer

Less than 1

Answer

0

Answer

1

Answer

Greater than 1

Question 10

Which method is effective in improving the power factor of an inductive circuit?

Accepted Answer

Adding a capacitor in parallel

Answer

Adding an inductor in series

Answer

Decreasing the voltage

Answer

Increasing the frequency

Question 11

In a transformer, how does increasing the number of turns on the secondary winding affect the output voltage?

Accepted Answer

Increases

Answer

Decreases

Answer

Changes the phase angle

Answer

Remains the same

Question 12

In an AC circuit, for an inductive load, how does voltage relate to current?

Accepted Answer

Voltage leads current

Answer

Current leads voltage

Answer

They are in phase

Answer

They are 180 degrees out of phase

Question 13

In an AC circuit, what is the SI unit of impedance?

Accepted Answer

Ohms (Ω)

Answer

Volts (V)

Answer

Amps (A)

Answer

Hertz (Hz)

Question 14

In AC circuit analysis, what is the purpose of a phasor diagram?

Accepted Answer

To represent the magnitude and phase angle of AC quantities

Answer

To calculate the power factor

Answer

To determine the resonant frequency

Answer

To measure the impedance

Question 15

Which AC circuit component stores energy in a magnetic field?

Accepted Answer

Inductor

Answer

Resistor

Answer

Capacitor

Answer

Diode

Question 16

In an AC circuit, what is the resonant frequency?

Accepted Answer

The frequency at which the impedance is minimum

Answer

The frequency at which the current is maximum

Answer

The frequency at which the voltage is maximum

Answer

The frequency at which the power factor is 1

Question 17

In an AC circuit, what is the primary function of a transformer?

Accepted Answer

To change the voltage level

Answer

To change the current level

Answer

To change the frequency

Answer

To change the power factor

Question 18

How does the inductive reactance of an inductor change as the frequency of the AC signal increases?

Accepted Answer

Inductive reactance increases.

Answer

Inductive reactance decreases.

Answer

Inductive reactance remains unchanged.

Question 19

Impedance in an AC circuit represents the total opposition to the flow of alternating current and is given by:

Accepted Answer

Impedance

Answer

Resistance

Answer

Reactance

Answer

Capacitance

Question 20

In a series RLC circuit, the voltage across the individual components will be:

Accepted Answer

Out of phase

Answer

In phase

Answer

90 degrees out of phase

Answer

180 degrees out of phase

Question 21

The appropriate instrument for measuring power in AC circuits is a:

Accepted Answer

Wattmeter

Answer

Voltmeter

Answer

Ammeter

Answer

Ohmmeter

Question 22

Power factor in an AC circuit is a measure of:

Accepted Answer

Efficiency of power transmission

Answer

Capacitance of the circuit

Answer

Inductance of the circuit

Answer

Resistance of the circuit

Question 23

The resonant frequency of a series RLC circuit occurs when:

Accepted Answer

Inductive reactance equals capacitive reactance

Answer

Inductive reactance exceeds capacitive reactance

Answer

Capacitive reactance exceeds inductive reactance

Answer

Resistance is zero

Question 24

In an AC circuit, the ratio of true power to apparent power is known as:

Accepted Answer

Power factor

Answer

Impedance

Answer

Phasor

Answer

Reactance

Question 25

In an AC circuit, how does the impedance of a capacitor vary as the frequency increases?

Accepted Answer

Decreases inversely proportional to frequency

Answer

Increases linearly

Answer

Remains constant

Answer

Changes unpredictably

Question 26

How does a low power factor affect the efficiency of an AC circuit?

Accepted Answer

Decreases circuit efficiency

Answer

Increases circuit efficiency

Answer

No impact on circuit efficiency

Answer

Increases circuit power

Question 27

In an AC circuit, what is the formula for calculating the total impedance of resistors and capacitors connected in series?

Accepted Answer

Z = R + jX_C

Answer

Z = R - jX_C

Answer

Z = 1/(R + jX_C)

Answer

Z = (R + jX_C)^2

Question 28

In an AC circuit, the phase angle between voltage and current is primarily determined by:

Accepted Answer

Impedance

Answer

Resistance alone

Answer

Capacitance alone

Answer

Inductance alone

Question 29

Which device is used to measure power in AC circuits?

Accepted Answer

Wattmeter

Answer

Ammeter

Answer

Voltmeter

Answer

Ohmmeter

Question 30

A transformer has a turns ratio of 10:1. If the primary voltage is 240V, calculate the secondary voltage:

Accepted Answer

24V

Answer

12V

Answer

480V

Answer

120V

Question 31

In an AC circuit, the phase difference between voltage and current is influenced primarily by which of the following factors?

Accepted Answer

The circuit's impedance.

Answer

The voltage amplitude only.

Answer

The current amplitude only.

Answer

The frequency of the AC supply only.

Question 32

To improve the power factor of an inductive AC circuit, which component can be added?

Accepted Answer

Capacitor

Answer

Inductor

Answer

Diode

Answer

Resistor

Question 33

What is a key safety precaution to follow when working with AC circuits?

Accepted Answer

Never make contact with exposed conductors.

Answer

Always wear rubber gloves.

Answer

Stand on a rubber mat.

Answer

Ensure adequate lighting.

Question 34

Which of the following is a benefit of three-phase AC systems over single-phase systems?

Accepted Answer

Increased power transmission efficiency and reduced energy losses.

Answer

Easier to generate

Answer

Higher voltage levels

Question 35

What is the term used to describe the opposition to the flow of alternating current in an AC circuit?

Accepted Answer

Impedance

Answer

Resistance

Answer

Inductance

Question 36

In an AC circuit, what does the angle between the voltage and current phasors represent?

Accepted Answer

Power factor

Answer

Frequency

Answer

Impedance

Question 37

Which component in an AC circuit stores energy in a magnetic field?

Accepted Answer

Inductor

Answer

Resistor

Answer

Capacitor

Answer

Transformer

Question 38

In a purely capacitive AC circuit, how does the current relate to the voltage?

Accepted Answer

Leads the voltage by 90 degrees

Answer

Lags the voltage by 90 degrees

Answer

Is in phase with the voltage

Answer

Has a zero phase angle

Question 39

What is the formula for calculating the power dissipated in an AC circuit?

Accepted Answer

VIcos(phi)

Answer

I^2/R

Answer

VIsin(phi)

Answer

V^2/R

Question 40

What is the primary function of a transformer in an AC circuit?

Accepted Answer

Change the voltage level

Answer

Change the frequency

Answer

Change the current level

Question 41

What is the term used to describe the ratio of the number of turns on the primary winding to the number of turns on the secondary winding in a transformer?

Accepted Answer

Turns ratio

Answer

Voltage ratio

Answer

Current ratio

Question 42

What determines the frequency of an AC circuit?

Accepted Answer

The source of the AC voltage

Answer

The load

Answer

The power factor

Answer

The circuit components