Exam 1 Big Review

Question 1

Left hand rule

Answer 1

thumb points with current, fingers show magnetic field

Question 2

left hand rule (generators)

Answer 2

thumb shows force direction
index for magnetic field
middle finger for direction of current

Question 3

conductor

Answer 3

gives atoms, nearly empty shell

Question 4

insulator

Answer 4

takes atoms, nearly full shell

Question 5

Control device

Answer 5

controls flow of current

Question 6

power producer

Answer 6

produces current

Question 7

power consumer

Answer 7

uses current

Question 8

resistors have what purpose

Answer 8

stop current to maintain stable resistance in various environments

Question 9

transformer

Answer 9

increases or decreases AC voltage in a circuit

Question 10

relay disadvantages

Answer 10

big heavy, slow, uses a lot of power

Question 11

solenoid advantages

Answer 11

stronger, carries higher current

Question 12

point of shielded wire

Answer 12

shields electrical interference - used for audio signal and high frequency

Question 13

why is solder flux used

Answer 13

prevents oxidation in solder

Question 14

wet cells are used in

Answer 14

aircraft, automotive, standby telecommunications

Question 15

VRLA battery advantage

Answer 15

low maintenance, cannot spill

Question 16

Gel Cell usage

Answer 16

acrobatic aircraft

Question 17

gel cells

Answer 17

recombinant battery (produces water) but needs pressure relieve valve

Question 18

lead-acid battery usage

Answer 18

smaller aircraft

Question 19

lead-acid battery characteristics

Answer 19

less expensive, bad power to weight ratio

Question 20

nickle cadmium battery usage

Answer 20

turbine aircraft

Question 21

nickel cadmium battery advantages

Answer 21

greater power to weight ratio
closed circuit voltage (near constant until dead)

Question 22

lithium ion battery usage

Answer 22

portable electronics

Question 23

lithium ion battery advantages

Answer 23

no memory effect, best weight - energy ratio, higher voltages

Question 24

potential problems with lithium ion batteries

Answer 24

thermal runaway

Question 25

generator armature

Answer 25

rotates carries current

Question 26

generator field

Answer 26

stationary magnetic field

Question 27

generator commutator

Answer 27

changes AC to DC

Question 28

generator brushes

Answer 28

electrical contacts allowing current path for power to leave

Question 29

alternator field

Answer 29

rotates, creates magnetic field

Question 30

alternator armature

Answer 30

stator, produces voltage

Question 31

alternator rectifier

Answer 31

changes AC to DC with diodes

Question 32

3 Phase power advantage

Answer 32

constant power supplied provides greater power density at same amperage smaller wires, lighter load, lower cost

Question 33

why is Alt > Gen

Answer 33

lighter, cheaper, more reliable, less maintenance needed

Question 34

what does a regulator do

Answer 34

controls field strength to keep generator output at necessary volt/current for variable load

Question 35

regulator inputs

Answer 35

mechanical / electrical energy

Question 36

regulator output

Answer 36

voltage / current from armature

Question 37

vibrator regulator

Answer 37

older, uses electromagnet

Question 38

regulator transistor advantages

Answer 38

cheaper, lighter, more reliable, longer MTBF smaller input controls larger output uses control valve

Question 39

zener diode

Answer 39

voltage sensitive controls transistors no moving parts

Question 40

load meter

Answer 40

measures alternator current starts at zero shows load on alternator

Question 41

ammeter

Answer 41

zero in center, shows charging rate

Question 42

series

Answer 42

one current path constant CURRENT

Question 43

parallel

Answer 43

more than one current path ( divided flow ) constant VOLTAGE

Question 44

DC current usages

Answer 44

batteries, portable/movable systems CONSTANT POLARITY

Question 45

AC usages

Answer 45

houses, large aircraft POLARITY CHANGES

Question 46

rectifier

Answer 46

AC to DC

Question 47

inverter

Answer 47

DC to AC (complex and expensive)

Question 48

DC advantages

Answer 48

portable backup power starts engine

Question 49

AC advantages

Answer 49

easily converted three phase gives more power

Question 50

single wire used

Answer 50

in metal aircraft

Question 51

two wire used

Answer 51

in composite aircraft

Question 52

which type of aircraft needs a ground conductor

Answer 52

composite aircraft

Question 53

Bus hierarchy

Answer 53

most important bus least likely to lose electrical power hot battery bus always connected to battery