PHEP 17

Question 1

What best defines a cycle

Answer 1

two alternations, one in each direction

Question 2

How many times larger is the max voltage value than the effective voltage value

Answer 2

0.707

Question 3

what is another name for effective values

Answer 3

root mean square value

Question 4

Does an AC amp produces heat at the same rate as a DC amp

Answer 4

yes

Question 5

what is the direction of a vector indicated by

Answer 5

a line segment and arrow

Question 6

what is the magnitude of a vector indicated by

Answer 6

length of line

Question 7

in what direction is positive rotation of a vector

Answer 7

counter clockwisewha

Question 8

what effect does self induced voltage have on applied voltage

Answer 8

it opposes it and reduces effectiveness

Question 9

what variables determine inductive reactance

Answer 9

2pi constant, frequency, inductance

Question 10

what is the relationship between current and applied voltage in a purely inductive circuit

Answer 10

current lags 90 degrees

Question 11

What are the two factors that limit current in an inductive circuit?

Answer 11

inductive reactance and resistance

Question 12

in a purely inductive reactant and resistant circuit what is the current applied voltage relationship

Answer 12

current lags by 45 degrees

Question 13

what are the units of capacity

Answer 13

farrads

Question 14

what is power factor

Answer 14

ratio of true power to apparent power

Question 15

AC meters and instruments are designed to read _____ voltage and currents.

Answer 15

Effective.

Question 16

The effective values of voltage and current are equal to the maximum values multiplied by?

Answer 16

.707

Question 17

The three factors that limit the flow of current in an AC circuit are?

Answer 17

1. Resistance
2. Inductive reactance
3. Capacitive reactance

Question 18

In a pure resistance circuit, voltage and current are?

Answer 18

In phase.

Question 19

In an AC circuit, what represents total Opposition to current and what is the symbol?

Answer 19

Impedance, Z

Question 20

What is the symbol for inductive reactance?

Answer 20

XL

Question 21

Whats used to determine inductive reactance?

Answer 21

The frequency and the amount of inductance in a circuit.

Question 22

What does ELI ICE represent?

Answer 22

ELI= voltage leads current (inductance)
ICE= current leads voltage (capacitve)

The letters represent the symbols for voltage, current, inductance, capacitance.

Question 23

Whats the relationship of voltage and current in a pure inductive circuit?

Answer 23

Voltage leads current by 90 degrees.

Question 24

Capacitive reactance varies inversely with?

Answer 24

The frequency and the size of the capacitor.

Question 25

In a pure capacitive circuit, voltage and current's relationship is?

Answer 25

out of phase 90 degrees, with current leading.

Question 26

What does VARs stand for?

Answer 26

Volt-ampere-reactive

Question 27

The power factor is equal to the cosine of the?

Answer 27

angle of phase difference between voltage and current.

Question 28

What is the measurement of the primary harmonic?

Answer 28

60hz

Question 29

What increments do harmonics go by?

Answer 29

60

Question 30

How can you reduce the third harmonic?

Answer 30

By connecting a set of winding's in a transformer in delta.

Question 31

Inductive reactance varies ______ with frequency.

Answer 31

Directly

Question 32

Capacitive reactance varies _______ with frequencty

Answer 32

Inversely

Question 33

Resonance is when?

Answer 33

Inductive reactance and capacitive reactance in a circuit cancels each other out and leaves only resistance.

Question 34

A 60-cycle AC current reverses its direction ______ times per second.

Answer 34

120