Deck 16: Alternating Voltage and Current

Question 1

When the amplitude of a sine wave is measured with an ac current meter, the value displayed by the meter will be the waveform's ______________ value.

Answer 1

rms

Question 2

The ______________ range includes frequencies that can be heard as sound waves by the human ear.

Answer 2

audio

Question 3

The amount of time it takes for one cycle is called the ______________.

Answer 3

period

Question 4

Short wavelengths for frequencies of 300 MHz or higher are called ______________.

Question 5

The symbol for a ______________ angle is θ.

Question 6

In an ac circuit with only ______________, the current variations are in phase with the applied voltage.

Question 7

The sawtooth wave is also referred to as a ______________ voltage.

Question 8

Exact multiples of the fundamental frequency are called ______________ frequencies.

Question 9

λ is the symbol used to represent ______________.

Question 10

A quantity that has magnitude and direction is a(n)

A) sinusoid
B) vector
C) phasor
D) parallelogram

Question 11

When two waveforms are exactly out of phase, what is the difference in degrees?

A) 90
B) 180
C) 270
D) 360

Question 12

Current variations are in phase with the applied voltage in an ac circuit with

A) resistors only
B) capacitors only
C) inductors only
D) resistors, capacitors, and inductors

Question 13

What electronic circuits produce sine-wave variations naturally?

A) Regulators
B) Oscillators
C) Amplifiers
D) Filters

Question 14

Which of the following is not a nonsinusoidal waveform?

A) Square wave
B) Sawtooth wave
C) Cosine wave
D) Pulse wave

Question 15

What type waveform is common in digital electronic circuitry?

A) Sine
B) Sawtooth
C) Cosine
D) Pulse

Question 16

Which of the following is an advantage of ac over dc power?

A) Higher voltages available
B) Greater efficiency in distribution
C) More popular in electronic circuits
D) Higher currents available

Question 17

Rules and regulations for residential wiring are usually based on which of the following?

A) NEC
B) FCC
C) IRS
D) IEEE

Question 18

In a motor, what connects to the electrical source that drives the motor?

A) Switching contacts
B) Solenoid
C) Coil
D) Armature

Question 19

What are graphic connectors that are spring-mounted in order to brush against the spinning rings on a rotor?

A) Field winding
B) Armature
C) Brushes
D) Slip rings

Question 20

Alternating current generators are

A) accelerators
B) motors
C) alternators
D) oscillators

Question 21

In an alternator with three generator windings equally spaced around the circle, the windings produce output voltages at

A) 120° out of phase with each other
B) 180° out of phase with each other
C) 90° out of phase with each other
D) 270° out of phase with each other

Question 22

Which of the following is not an advantage of three-phase ac voltage?

A) More efficient distribution of power
B) Induction motors are self-starting
C) Ripple is easier to filter
D) Less complicated configurations

Question 23

The number of cycles per second is the frequency measured in

A) gilberts
B) maxwells
C) siemens
D) hertz

Question 24

Which of the following test equipment is generally used to view and measure ac waveforms?

A) Oscilloscope
B) Voltmeter
C) DMM
D) Frequency counter

Question 25

One complete revolution of an ac waveform is a(n)

A) harmonic
B) alternation
C) pulse
D) cycle

Question 26

What symbol is used to represent the ratio of the circumference to the diameter for any circle?

A) ?
B) ?
C) ?
D) $\pi$

Question 27

The numerical value ofis $\pi$

A) 3.1416
B) 4.1316
C) 0.707
D) 1.414

Question 28

For a complete sine wave of alternating voltage, the average value is

A) 1.414 V
B) 0.707 V
C) 3.1416 V
D) 0 V

Question 29

Alternating voltage continuously varies in amplitude and periodically reverses polarity.

Question 30

The basic function of an oscilloscope is to view dc waveforms.

Question 31

One complete revolution of a waveform is called a cycle.

Question 32

The full-cycle of revolution is also called an alternation.

Question 33

The numerical value of $\pi$ is 1.314.

Question 34

A sine wave is proportional to the sine of an angle of rotation in the circular motion producing the voltage.

Question 35

When a sine wave of alternating voltage is connected across a load resistance, the current that flows in the circuit is a cosine wave.

Question 36

The peak value is the maximum value of a sine wave.

Question 37

The dc value of a waveform is its average value over one complete cycle.

Question 38

When the amplitude of a sine wave is measured with an ac voltmeter, the value displayed by the meter will be the average value.

Question 39

The rms value of a sine wave is equal to 0.707 times peak value.

Question 40

An oscilloscope cannot measure or display the peak-to-peak values of an ac waveform.

Question 41

Sound waves above the audible range of frequencies are called ultrasonic waves.

Question 42

To compare the phase relationship between two ac sine waves, both sine waves must have exactly the same frequency.