Master Alternating Current: A Comprehensive Guide for Electrical Engineering Students

Question 1

Which property is NOT characteristic of alternating current (AC)?

Accepted Answer

AC is always a sine wave

Answer

Voltage can be increased or decreased using transformers

Answer

AC can cause an electromotive force (EMF)

Answer

AC can be generated by an alternator

Question 2

In the United Kingdom, what is the frequency of the AC supply?

Accepted Answer

50 Hz

Answer

60 Hz

Answer

75 Hz

Answer

100 Hz

Question 3

Which device converts alternating current (AC) to direct current (DC)?

Accepted Answer

Rectifier

Answer

Transformer

Answer

Inductor

Answer

Capacitor

Question 4

What is the unit of measurement for AC current?

Accepted Answer

Ampere (A)

Answer

Volt (V)

Answer

Watt (W)

Answer

Ohm (Ω)

Question 5

What is the mathematical formula for calculating the Root Mean Square (RMS) value of alternating current?

Accepted Answer

Integrate the square of the waveform over one cycle and then take the square root

Answer

Sum the values of the waveform over one cycle

Question 6

What is the primary method used to generate alternating current (AC)?

Accepted Answer

Electromagnetic induction

Answer

Electrostatic induction

Answer

Chemical reaction

Question 7

How does the frequency of an alternating current impact the appearance of its sine wave?

Accepted Answer

It alters the number of peaks and troughs within a specific time frame.

Answer

It modifies the wave's amplitude.

Answer

It transforms the wave's shape from a sine wave to a square wave.

Question 8

Which of the following is the unit of electrical resistance, commonly used to express the ability of a material to oppose the flow of electric current?

Accepted Answer

Ohm

Answer

Ampere

Answer

Volt

Answer

Watt

Question 9

In a sine wave, what is the relationship between the peak voltage and the RMS voltage?

Accepted Answer

Peak voltage is the square root of 2 times the RMS voltage

Answer

Peak voltage is twice the RMS voltage

Answer

Peak voltage is equal to the RMS voltage

Answer

Peak voltage is half the RMS voltage

Question 10

Which of the following is NOT a characteristic associated with alternating current (AC)?

Accepted Answer

Maintains constant amplitude

Answer

Periodically reverses direction

Answer

Has a defined frequency

Answer

Generates electromagnetic fields

Question 11

In a purely inductive AC circuit, what is the phase difference between the voltage and current?

Accepted Answer

90 degrees

Answer

0 degrees

Answer

45 degrees

Answer

180 degrees

Question 12

Which characteristic is NOT associated with alternating current (AC)?

Accepted Answer

Straight-line waveform

Answer

Periodic reversal of direction

Answer

Generation via a rotating magnetic field

Answer

Frequency measurement in Hertz (Hz)

Question 13

What value represents the maximum positive or negative amplitude of a sine wave?

Accepted Answer

Peak value

Answer

Average value

Answer

Root mean square (RMS) value

Answer

Half the amplitude

Question 14

Which formula accurately calculates the RMS value of an AC voltage?

Accepted Answer

Vrms = Vpeak / √2

Answer

Vrms = Vpeak

Answer

Vrms = Vpeak * √2

Answer

Vrms = Vpeak / 2

Question 15

In an AC circuit, which component results in the current being in phase with the voltage?

Accepted Answer

Resistance only

Answer

Inductance only

Answer

Capacitance only

Answer

Both resistance and inductance

Question 16

Which factors influence the inductive reactance of an inductor?

Accepted Answer

Both inductance and frequency

Answer

Inductance alone

Answer

Frequency alone

Answer

Neither inductance nor frequency

Question 17

What is the primary purpose of a capacitor in an AC circuit?

Accepted Answer

Storing energy in an electric field

Answer

Impeding current flow

Answer

Increasing circuit voltage

Answer

Reducing current frequency

Question 18

Which type of motor is NOT an AC motor?

Accepted Answer

Commutator motor

Answer

Induction motor

Answer

Synchronous motor

Answer

Stepper motor

Question 19

When transmitting power over long distances, what is the main advantage of alternating current (AC) over direct current (DC)?

Accepted Answer

Easier voltage transformation

Answer

Reduced losses due to the skin effect

Answer

Smaller conductors for equivalent power transmission

Answer

Enhanced safety in hazardous environments

Question 20

An AC waveform oscillates 50 times in one second. What is its frequency?

Accepted Answer

50 Hz

Answer

0.05 Hz

Answer

5000 Hz

Answer

500 Hz

Question 21

In an AC circuit, the RMS voltage (Vr) is related to the peak voltage (Vp) as:

Accepted Answer

Vr = Vp / √2

Answer

Vr = Vp

Answer

Vr = Vp / 2

Answer

Vr = Vp × √2

Question 22

Which property of an inductor opposes changes in current flow?

Accepted Answer

Inductive reactance

Answer

Resistance

Answer

Capacitive reactance

Answer

Impedance

Question 23

In an AC circuit, a capacitor primarily:

Accepted Answer

Stores energy in an electric field

Answer

Generates AC voltage

Answer

Blocks AC current

Answer

Acts as a resistor

Question 24

In a purely resistive AC circuit, the phase angle between voltage and current is:

Accepted Answer

0 degrees

Answer

180 degrees

Answer

90 degrees

Answer

Varies with frequency

Question 25

Which AC circuit element consumes real power?

Accepted Answer

Resistor

Answer

Diode

Answer

Capacitor

Answer

Inductor

Question 26

The main function of a transformer in an AC power system is to:

Accepted Answer

Change voltage levels

Answer

Rectify AC to DC

Answer

Store energy

Answer

Control current flow

Question 27

Which major safety hazard is associated with high-voltage AC systems?

Accepted Answer

Electric shock

Answer

Magnetic field exposure

Answer

Thermal burns

Answer

Noise pollution

Question 28

The key difference between a single-phase and a three-phase AC system lies in:

Accepted Answer

Number of conductors and phase shifts

Answer

Voltage levels

Answer

Frequency

Answer

Power capacity