Electricity 4 of 7

Question 1

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.

Answer 1

Time relationship

Question 2

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

Answer 2

Resistive

Question 3

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

Answer 3

Inductive

Question 4

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

Answer 4

Capacitive

Question 5

Every physical quantity has?

Answer 5

Magnitude

Question 6

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

Answer 6

Scalar

Question 7

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

Answer 7

A vector

Question 8

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

Answer 8

Length of the line

Question 9

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

Answer 9

Horizontal axis

Question 10

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

Answer 10

Addition and subtraction

Question 11

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

Answer 11

Resultant vector or just resultant

Question 12

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

Answer 12

Geometry and algebraic addition and subtraction

Question 13

To add vector quantities that have the same direction you?

Answer 13

Add the individual magnitudes.

Question 14

To add vector quantities that have different directions you?

Answer 14

Subtract the smaller vector from the larger vector.

Question 15

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.

Answer 15

Parallelogram method

Question 16

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

Answer 16

Place the vectors “tail to tail.”

Question 17

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

Answer 17

Diagonal (hypotenuse)

Question 18

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

Answer 18

Head to tail.

Question 19

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

Answer 19

The tail The head

Question 20

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

Answer 20

90

Question 21

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

Answer 21

Pythagorean theorem

Question 22

The sum of the angles in a right triangle equals?

Answer 22

180 degrees

Question 23

What is opposite of the right angle of a triangle?

Answer 23

The hypotenuse

Question 24

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

Answer 24

1- sine 2- co-sign 3- tangent

Question 25

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

Answer 25

Negative

Question 26

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

Answer 26

None.

Question 27

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

Answer 27

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

Question 28

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

Answer 28

The direction

Question 29

A-c vectors are called?

Answer 29

Rotating vectors

Question 30

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

Answer 30

Meaningless

Question 31

The length of a vector shows its\_\_\_\_\_\_\_\_\_, while the angle between the vectors shows the \_\_\_\_\_\_\_.

Answer 31

Amplitude Phase

Question 32

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

Answer 32

Less than 180 degrees

Question 33

A waveform shows what values?

Answer 33

Instantaneous

Question 34

What values do vectors provide?

Answer 34

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

Question 35

An RL circuit contains both?

Answer 35

Resistance and inductance.

Question 36

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

Answer 36

Resistive circuit

Question 37

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

Answer 37

Inductive circuit

Question 38

Only quantities that vary in _________ can differ in phase?

Answer 38

Time

Question 39

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

Answer 39

Z Ohms

Question 40

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

Answer 40

When the other value is 10 time the resistance value.

Question 41

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.

Answer 41

In phase, Leads

Question 42

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

Answer 42

By using Pythagoras theorem

Question 43

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

Answer 43

Tan of(EL/ER)

Question 44

What does Impedance represent?

Answer 44

Total opposition to current flow.

Question 45

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

Answer 45

All

Question 46

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

Answer 46

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

Question 47

What two types of power are in RL circuits?

Answer 47

Apparent and true power

Question 48

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

Answer 48

True power. Ptrue=I^2R

Question 49

What is the power factor equation?

Answer 49

True power/apparent power

Question 50

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

Answer 50

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

Question 51

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

Answer 51

The same as the applied voltage.

Question 52

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

Answer 52

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

Question 53

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

Answer 53

Pythagoras theorem

Question 54

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

Answer 54

Leads 90

Question 55

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

Answer 55

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

Question 56

How does frequency affect impedance in a series RL circuit?

Answer 56

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