Test Review

Question 1

Inductors always _______ a change in current.

Answer 1

Oppose

Question 2

When current flows through a conductor, what is created?

Answer 2

Magnetic field

Question 3

What are the important factors concerning electromagnetic induction?

Answer 3

• a conductor
• relative motion
• magnetic field

Question 4

An induced voltage or current _______ the motion that causes it.

Answer 4

Opposes

Lenz’s Law

Question 5

What is the greatest advantage of AC?

Answer 5

It can be transformed

Question 6

The _______ must be found when a sine wave AC voltage is changed into DC with a rectifier?

Answer 6

Average

Question 7

What is the formula to find RMS value?

Answer 7

RMS = peak * .707

Question 8

Resistive loads are characterized by the fact that they…

Answer 8

• produce heat

- voltage and current are in phase

Question 9

A sine wave contains _______ degrees.

Answer 9

360

Question 10

What is a line that indicates both magnitude and direction?

Answer 10

Vector

Question 11

What is the formula for instantaneous voltage?

Answer 11

E (isnt) = E(max) * sin(theta)

Question 12

What three factors determine the amount of voltage induced?

Answer 12

• number of turns of a wire
• strength of magnetic flux (flux density)
• speed of cutting action

Question 13

Each complete waveform of 360 degrees is called a _______.

Answer 13

Cycle

Question 14

What is the sum of all angles of a triangle?

Answer 14

180 degrees

Question 15

What is the unit of measurement for inductance?

Answer 15

Henrys (H)

Question 16

The amount of inductance on a coil is determined by what two things?

Answer 16

• space between the windings

- physical properties and construction

Question 17

What is the most common of all AC waveforms?

Answer 17

Sine wave

Question 18

The _______ of the induced voltage can also be changed by reversing the _______ of the magnetic field.

Answer 18

Polarity; polarity

Question 19

What does RMS stand for?

Answer 19

Root mean square

Question 20

What is the formula to solve for RMS value?

Answer 20

RMS = peak * .707

Question 21

What is a cycle?

Answer 21

A complete waveform

Question 22

What can AC do that DC cannot?

Answer 22

Transform

Question 23

Vector is a line that determines _______ and _______.

Answer 23

Magnitude; direction

Question 24

What is the Pythagorean theorem?

Answer 24

c^2 = a^2 + b^2

Question 25

What is a Henry?

Answer 25

Unit of measurement for inductance

Question 26

_______ always oppose a change of _______.

Answer 26

Inductors; current

Question 27

_______ opposes the motion that causes it.

Answer 27

Induced voltage

Question 28

What is a voltage spike?

Answer 28

When current flow through an inductor stops, and the current also decreases at an exponential rate

Question 29

1 Weber = _______ lines of flux

Answer 29

100,000,000

Question 30

The _______ describes the rate of certain occurrences and is divided into _______ time constants

Answer 30

Exponential curve; 5

Question 31

During each time constant, how much does the current rise?

Answer 31

63.2%

Question 32

What is electromagnetic induction?

Answer 32

When a conductor cuts through magnetic lines of flux, a voltage is induced into the conductor.

Question 33

The number of cycles completed in one second is called?

Answer 33

Frequency

Question 34

What type of wave is the triangle wave?

Answer 34

Linear wave

Question 35

What electronic component is often used to prevent large voltage spikes from being produced when the current flow is terminated?

Answer 35

Diode

Question 36

Induced voltage is always _______ in polarity to the _______ voltage.

Answer 36

Opposite; applied

Question 37

What opposes a change of current?

Answer 37

Inductors

Question 38

Inductors can produce _______ when the current stops flowing through them.

Answer 38

Voltage spikes or extremely high voltages

Question 39

What are two devices to help prevent large spike voltages?

Answer 39

Resistors and diodes

Question 40

In an R-C circuit, the current flow through the capacitor will be _______ out of phase with the current flow through the resistor.

Answer 40

90 degrees

Question 41

In a parallel connected R-C circuit, the voltage will be _______ through all devices.

Answer 41

The same

Question 42

In an AC R-L circuit, the total current I is equal to the applied voltage divided by _______.

Answer 42

Impedance (Z)

Question 43

When AC voltage is being measured with a voltmeter, which value of AC voltage will be indicated?

Answer 43

RMS

Question 44

How many degrees are there in one complete cycle of alternating voltage?

Answer 44

360

Question 45

A sine wave has a peak or max value of _______ voltage. (What is the formula)

Answer 45

E (inst) = E(max) x sin(theta)

Question 46

What best describes average voltage?

Answer 46

The amount of voltage that would be measured by a DC voltmeter after a sine wave AC voltage has been rectified with a full wave rectifier.

Question 47

What best describes RMS voltage?

Answer 47

The amount of AC voltage that will produce as much power as a like amount of pure DC voltage.

Question 48

What is the relationship of current and voltage in a pure resistive circuit?

Answer 48

In phase

Question 49

Vectors are lines that indicate...

Answer 49

Magnitude and direction

Question 50

What is the relationship of current and voltage in a pure conductive circuit?

Answer 50

Current leads voltage by 90 degrees

Question 51

What would limit the amount of current flow in a pure inductive circuit?

Answer 51

Inductive reactance

Question 52

What three factors determine the amount of capacitance a capacitor will have?

Answer 52

- surface area of plates - distance between the plates - type of dielectric used

Question 53

What is the unit of capacitance?

Answer 53

Farads

Question 54

What is the total resistance in a purely inductive circuit called?

Answer 54

Inductive reactance