Final Unit Test

Question 1

what is the phase relationship between current and voltage in an inductor for an ac circuit

Answer 1

voltage leads current by 90 degrees

Question 2

x is

Answer 2

reactance in ohms

Question 3

how does a capacitor differ from a resistor

Answer 3

a capacitor does not dissipate any energy as a resistor does, it only stores it during a portion of the ac cycle and returns it to the source during another portion of the cycle

Question 4

inductive reactance and capacitive reactance both ______ current

Answer 4

Both appose current.

Question 5

L

Answer 5

inductance in hennrys

Question 6

reactive power

Answer 6

VARs - the product of volts and amps that are 90 degrees our of phase with each other.

Question 7

pf formula

Answer 7

(W/VA)(100)

Question 8

how to find total inductance in series?

Answer 8

sum of the inductors

Question 9

the power factor of a RLC circuit is the ratio of

Answer 9

true power to apparent power written as a percentage

Question 10

pf

Answer 10

power factor

Question 11

What two factors determine inductive reactance of an inductor

Answer 11

frequency and inductance

Question 12

in a purely resistive circuit voltage and current are ________.

Answer 12

in phase

Question 13

as frequency increases inductive reactance _______.

Answer 13

increases

Question 14

in a series LC circuit the voltage drop across the inductor ______ current by ______ degrees

Answer 14

leads , 90

Question 15

reactive power is measured in

Answer 15

VARs

Question 16

formula for inductive reactance

Answer 16

Xl = 2πFL

Question 17

F

Answer 17

frequency in Hz

Question 18

in a series LC circuit the voltage drop across the capacitor ____ current by _____ degrees

Answer 18

lags, 90

Question 19

apparent power

Answer 19

VA - the value found if circuit voltage and current are multiplied together

Question 20

how do you find total capacitance in parrallel

Answer 20

sum of the capacitors

Question 21

a capacitor ______ dc but allows a ________ current to pass because of the _______ voltage.

Answer 21

blocks, changing, changing

Question 22

in a purely inductive circuit voltage and current are?

Answer 22

90 degrees out of phase

Question 23

when the voltage of a series RL circuit is increased impedance will

Answer 23

stay the same

Question 24

as frequency increases capacitive reactance_______.

Answer 24

decreases

Question 25

how do you find total capacitance in series?

Answer 25

use the reciprocal equation

Question 26

capacitive reactance formula

Answer 26

1/(2πFC)

Question 27

What factors determine the capacitive reactance of a capacitor

Answer 27

frequency, capacitance

Question 28

Xl

Answer 28

inductive reactance

Question 29

true power is measured in

Answer 29

watts

Question 30

what is the phase relationship between current and voltage in a capacitor for and ac circuit

Answer 30

current leads voltage by 90 degrees

Question 31

the higher the power factor percentage the more______ a circuit opperation

Answer 31

efficient

Question 32

Xc is

Answer 32

capacitive reactance

Question 33

va

Answer 33

volts amps

Question 34

Z

Answer 34

impedance in ohms

Question 35

in a purely resistive circuit the phase shift between voltage and current is

Answer 35

0 degrees

Question 36

as frequency is increased in an RC series circuit total impedance will

Answer 36

decrease

Question 37

apparent power is measured in

Answer 37

VAs

Question 38

vars

Answer 38

volts amps resistance

Question 39

in a series RL circuit voltage and current are?

Answer 39

our of phase somewhere between 0 and 90 degrees

Question 40

capacitors ________ a change in voltage

Answer 40

oppose

Question 41

true power

Answer 41

measured in watts and equal to the value of apparent power when current and voltage are in phase

Question 42

when frequency _______ resistance ________.

Answer 42

raise, raise