# Test Review Flashcards Preview

## Advanced Electricity > Test Review > Flashcards

Flashcards in Test Review Deck (54)
1
Q

Inductors always _______ a change in current.

A

Oppose

2
Q

When current flows through a conductor, what is created?

A

Magnetic field

3
Q

What are the important factors concerning electromagnetic induction?

A
• a conductor
• relative motion
• magnetic field
4
Q

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

A

Opposes

Lenz’s Law

5
Q

What is the greatest advantage of AC?

A

It can be transformed

6
Q

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

A

Average

7
Q

What is the formula to find RMS value?

A

RMS = peak * .707

8
Q

Resistive loads are characterized by the fact that they…

A
• produce heat

- voltage and current are in phase

9
Q

A sine wave contains _______ degrees.

A

360

10
Q

What is a line that indicates both magnitude and direction?

A

Vector

11
Q

What is the formula for instantaneous voltage?

A

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

12
Q

What three factors determine the amount of voltage induced?

A
• number of turns of a wire
• strength of magnetic flux (flux density)
• speed of cutting action
13
Q

Each complete waveform of 360 degrees is called a _______.

A

Cycle

14
Q

What is the sum of all angles of a triangle?

A

180 degrees

15
Q

What is the unit of measurement for inductance?

A

Henrys (H)

16
Q

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

A
• space between the windings

- physical properties and construction

17
Q

What is the most common of all AC waveforms?

A

Sine wave

18
Q

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

A

Polarity; polarity

19
Q

What does RMS stand for?

A

Root mean square

20
Q

What is the formula to solve for RMS value?

A

RMS = peak * .707

21
Q

What is a cycle?

A

A complete waveform

22
Q

What can AC do that DC cannot?

A

Transform

23
Q

Vector is a line that determines _______ and _______.

A

Magnitude; direction

24
Q

What is the Pythagorean theorem?

A

c^2 = a^2 + b^2

25
Q

What is a Henry?

A

Unit of measurement for inductance

26
Q

_______ always oppose a change of _______.

A

Inductors; current

27
Q

_______ opposes the motion that causes it.

A

Induced voltage

28
Q

What is a voltage spike?

A

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

29
Q

1 Weber = _______ lines of flux

A

100,000,000

30
Q

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

A

Exponential curve; 5

31
Q

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

A

63.2%

32
Q

What is electromagnetic induction?

A

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

33
Q

The number of cycles completed in one second is called?

A

Frequency

34
Q

What type of wave is the triangle wave?

A

Linear wave

35
Q

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

A

Diode

36
Q

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

A

Opposite; applied

37
Q

What opposes a change of current?

A

Inductors

38
Q

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

A

Voltage spikes or extremely high voltages

39
Q

What are two devices to help prevent large spike voltages?

A

Resistors and diodes

40
Q

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

A

90 degrees

41
Q

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

A

The same

42
Q

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

A

Impedance (Z)

43
Q

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

A

RMS

44
Q

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

A

360

45
Q

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

A

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

46
Q

What best describes average voltage?

A

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.

47
Q

What best describes RMS voltage?

A

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

48
Q

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

A

In phase

49
Q

Vectors are lines that indicate…

A

Magnitude and direction

50
Q

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

A

Current leads voltage by 90 degrees

51
Q

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

A

Inductive reactance

52
Q

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

A
• surface area of plates
• distance between the plates
• type of dielectric used
53
Q

What is the unit of capacitance?

A