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RWD OP 1ST 6 MONTHS > Electricity 4 of 7 > Flashcards

Electricity 4 of 7 Flashcards

1
Q

The term “phase angle” is used to describe the ___________ ___________ between a-c voltages and currents, as well as to specify a position or point in time of one a-c voltage or current.

A

Time relationship

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2
Q

In a purely _________ circuit, the voltage and current are in phase.

A

Resistive

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3
Q

In a purely ____________ circuit, the applied voltage leads the current by 90 degrees.

A

Inductive

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4
Q

In a purely _______________ circuit, the current leads the applied voltage by 90 degrees.

A

Capacitive

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5
Q

Every physical quantity has?

A

Magnitude

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6
Q

What do you call a quantity that only has a magnitude?

A

Scalar

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7
Q

What do you call a quantity that has magnitude and direction?

A

A vector

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8
Q

The _________ of the __________ is proportional to the magnitude of the vector quantity, and the ___________ indicates the direction.

A

Length of the line

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9
Q

When looking at a vector, what axis serves as the reference line?

A

Horizontal axis

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10
Q

In our line of work, we will only be interested in the ___________ and _________ of vectors. (Think math)

A

Addition and subtraction

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11
Q

When vectors are added or subtracted, the result is also a vector, and is called the _________ __________.

A

Resultant vector or just resultant

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12
Q

What combination of math is used to add and subtract vectors?

A

Geometry and algebraic addition and subtraction

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13
Q

To add vector quantities that have the same direction you?

A

Add the individual magnitudes.

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14
Q

To add vector quantities that have different directions you?

A

Subtract the smaller vector from the larger vector.

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15
Q

When vectors are not going in the same direction or in opposite directions, they can be added graphically and the resultant can be found using the __________ ____________ method.

A

Parallelogram method

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16
Q

What’s the first thing you do when adding vectors using the parallelogram method?

A

Place the vectors “tail to tail.”

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17
Q

The ___________ line is the resultant of the vectors after they have been placed tail to tail.

A

Diagonal (hypotenuse)

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18
Q

Another method for adding vectors is the triangle method and involves laying the vectors __________ to _________.

A

Head to tail.

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19
Q

The resultant of the triangle method is the line that starts at ____ ___________ of the first vector and ends at ____ ______ of the second vector.

A

The tail The head

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20
Q

Vectors that are not in same direction or in opposite directions are __ degrees apart.

A

90

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21
Q

The magnitude of the resultant of vectors, that are 90 degrees apart, can be determined by using what equation?

A

Pythagorean theorem

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22
Q

The sum of the angles in a right triangle equals?

A

180 degrees

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23
Q

What is opposite of the right angle of a triangle?

A

The hypotenuse

24
Q

What 3 trigonometric relationships can be used to find the angles of a triangle?

A

1- sine 2- co-sign 3- tangent

25
Q

When subtracting one vector from another, add the ___________ equivalent by rotating the vector 180 degrees.

A

Negative

26
Q

When rotating a vector 180 degrees to get its negative equivalent, what effect does this have on its magnitude?

A

None.

27
Q

Can a vector be separated? If so, what are their parts called?

A

Yes, and their parts are called the horizontal component and the vertical component.

28
Q

When adding vectors by there components, what must be determined before drawing the resultant vector?

A

The direction

29
Q

A-c vectors are called?

A

Rotating vectors

30
Q

A vector is _____________ until compared with the direction of another voltage or current vector.

A

Meaningless

31
Q

The length of a vector shows its_________, while the angle between the vectors shows the _______.

A

Amplitude Phase

32
Q

The angle between any vector and the reference vector is measured in the direction that will make it less than?

A

Less than 180 degrees

33
Q

A waveform shows what values?

A

Instantaneous

34
Q

What values do vectors provide?

A

Effective values, such as; peak, average, or effective value of the amplitude.

35
Q

An RL circuit contains both?

A

Resistance and inductance.

36
Q

In this circuit, resistance is the only opposition to current.

A

Resistive circuit

37
Q

In this circuit, inductance is the only opposition to current flow.

A

Inductive circuit

38
Q

Only quantities that vary in _________ can differ in phase?

A

Time

39
Q

What is the symbol for impedance and what is it measured in?

A

Z Ohms

40
Q

When can the value of resistance in a circuit be neglected?

A

When the other value is 10 time the resistance value.

41
Q

The voltage drop across a resistance is __ ______ with the current that causes it, while the voltage drop across an inductance _________ the current by 90 degrees.

A

In phase, Leads

42
Q

How do you find the voltage in a series RL circuit?

A

By using Pythagoras theorem

43
Q

How equation determines the phase angle between the voltage applied to the resistor and the applied voltage to the inductor?

A

Tan of(EL/ER)

44
Q

What does Impedance represent?

A

Total opposition to current flow.

45
Q

In resistive circuits, _____ of the Power delivered by the source is dissipated by the load.

A

All

46
Q

In an RL circuit, only part of the power delivered is dissipated. Where does the rest go?

A

It’s returned to the source each time the magnetic field collapses.

47
Q

What two types of power are in RL circuits?

A

Apparent and true power

48
Q

What power is is used by the resistance in an RL circuit and what is its equation?

A

True power. Ptrue=I^2R

49
Q

What is the power factor equation?

A

True power/apparent power

50
Q

What is the Q of a coil and what is the equation?

A

The Q of a coil is how close the coil is to being a perfect inducer and is a ratio of the reactance to the resistance of a coil. Q=XL/R

51
Q

The voltage across every branch in a parallel RL circuit is?

A

The same as the applied voltage.

52
Q

Is there a phase difference of current in a parallel RL circuit?

A

Yes, the resistive legs current is in phase with the voltage while the voltage in the inductive legs leads the current by 90 degrees.

53
Q

Since current in an RL circuit is out of phase, what equation is used to find their vector sum?

A

Pythagoras theorem

54
Q

In a RL circuit, resistive current _________ the inductive current by __ degrees.

A

Leads 90

55
Q

How Does increased frequency in a parallel RL circuit affect impedance?

A

The higher the frequency, the closer the impedance gets to the value of the resistance; making the circuit more resistive.

56
Q

How does frequency affect impedance in a series RL circuit?

A

A higher frequency increases the impedance of the circuit making the circuit more inductive

57
Q
A

RWD OP 1ST 6 MONTHS (16 decks)

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