Unit 16

Question 1

Effective ac voltage or effective ac current is the equivalent value of what?

Answer 1

dc voltage or dc current that would produce the same amount of heat in a resistor

Question 2

How do you calculate the frequency?

Answer 2

The number of times the rotor turns in one second

Question 3

(T/F) The waveform for alternating-current circuits is asymmetrical

Answer 3

False

Question 4

A waveform image is used to display the level and direction of _______ and ________

Answer 4

Current : Voltage

Question 5

In an AC generator, the magnitude of the voltage produced depends on what 3 things?

Answer 5

1) Number of turns of wire 2) Strength of the magnetic field 3) Speed at which the coil rotates

Question 6

What does RMS value stand for?

Answer 6

Root-Mean-Square

Question 7

Less current uses bigger or smaller conductor size?

Answer 7

Smaller

Question 8

How do you get non-symmetrical waveforms?

Answer 8

Combination of AC and DC wave forms

Question 9

In generators that produce large quantities of electricity, why would you use an electromagnet over a permanent magnet?

Answer 9

When using an electromagnet you can alter that magnetic field which therefore allows you to control the output voltage

Question 10

Most electricity in the US has a frequency of _____ Hz

Answer 10

60

Question 11

The value of the ac current or voltage waveform at a moment of time is called what?

Answer 11

Instantaneous value

Question 12

(T/F) The effects of electron movement change based on the direction of current flow

Answer 12

False

Question 13

When two waveforms are in step with each other, they are said to be ____

Answer 13

In-phase

Question 14

(T/F) The primary reason for using alternating current is because it’s inexpensive to transmit

Answer 14

True

Question 15

A direct-current waveform displays the direction and _____ of the current or voltage

Answer 15

Magnitude

Question 16

A three-phase generator has each of its windings out-of-phase with each other by ______ degrees

Answer 16

120

Question 17

Phase differences are often expressed in degrees; one full wave from equals ______ degrees

Answer 17

360

Question 18

What is the best way to know which waveform is leading or lagging?

Answer 18

Find out which waveform finished its cycle first

Question 19

When describing the relationship between voltage and current, the reference waveform is always ______

Answer 19

Voltage

Question 20

An alternating-current waveform displays the level and direction of the current and voltage for every instant of time for how many revolutions of the rotar?

Answer 20

One

Question 21

“Phase” is a term that indicates the _____ or ______ relationship between two waveforms.

Answer 21

Time : Degree

Question 22

When a magnetic field moves through a coil of wire, what causes the electrons in the wire to flow in a specific direction?

Answer 22

Lines of force of the magnetic field

Question 23

Electrons flow only when there is motion of the conductors relative to the ______ _____

Answer 23

Magnetic Field

Question 24

In generators that produce large quantities of electricity, which of these is stationary and which of them is not? Conductor Coils and Magnetic Field

Answer 24

The conductor coils are stationary and the magnetic field revolves within the coils

Question 25

The maximum value the ac current or voltage waveform reaches is called what?

Answer 25

Peak Value

Question 26

For a pure sine wave:

Answer 26

Effective value = RMS value

Question 27

What are two ways to express frequency?

Answer 27

Hertz or Cycles per second

Question 28

A nonsinusoidal waveform is created when nonlinear ____ distort the sine wave

Answer 28

Loads