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Exposures II > chapter 4- Electromagnetism > Flashcards

chapter 4- Electromagnetism Flashcards

1
Q

like charges repel
opposites attract
north pole and south pole

A

magnets

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2
Q

o Force between two magnetic fields directly proportional to product
of their magnitudes and inversely proportional to square of
distance between them

A

Inverse Square Law

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3
Q

magnets demonstrate :

A

polarity

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4
Q

inverse square law applies to :

A

-magnetism
-electric field
-gravity

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5
Q

A coiled, helix of wire carrying
an electrical current

A

Solenoid

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6
Q

required components for electromagnetic induction

A

Requires an interaction between a conductor and a magnetic field
o Magnetic field
o Conductor
o Relative motion

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7
Q

Two types of induction

A

-mutual induction
-self induction

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8
Q

-two coils
-varying current supplied to primary coil
-induces current in secondary coil
-two coils are electrically insulated from each-other

A

mutual induction

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9
Q

which induction requires step up and step down

A

mutual induction

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10
Q

which induction is primary to secondary

A

mutual

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11
Q

where is step down located

A

in the filament

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12
Q

what happens to the amps when volts is increased

A

amps decreases

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13
Q

what happens to voltage when mA is increased

A

voltage decreases

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14
Q

always present in coils supplied with alternating current

A

self induction

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15
Q

convert mechanical energy to electrical energy

A

generators

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16
Q

can produce direct current or alternating current

A

generators

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17
Q

components of generator

A

armature
magnets
slip rings
brushes

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18
Q

autotransformer and alternating current is your:

A

self induction

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19
Q

is alternating current rectified or uncertified

A

unrectified
full wave

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20
Q

is direct current rectified or unrecitified

A

rectified
1/2 wave

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21
Q

what is your source orgin for voltage

A

autotransformer

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22
Q

helps deliver current

A

step down

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23
Q

what design does the direct current generators use

A

a commutor ring design

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24
Q

what design does the alternating current generators use

A

slip rings

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25
Q

what circuit do you add all the numbers

A

series

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26
Q

what circuit do you take the lowest number and cut it in half

A

parallel

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27
Q

when 1 thing isnt working, the whole thing is down

A

series circuit

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28
Q

when 1 thing isnt working, just that area/ part isnt working

A

parallel circuit

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29
Q

olms law

A

V=IR
v=voltage
I=current
R=resistance

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30
Q

what is your unit for current

A

amperage

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31
Q

where is your step up and step down

A

step up - primary to secondary
step down - filament

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32
Q

what happens to your voltage when your amps is increased in step down

A

Voltage decreases

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33
Q

where is your rectifier located

A

secondary

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34
Q

is step down your current or voltage

A

current

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35
Q

what is volts changed to in step up

A

volts to kilovolts

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36
Q

line voltage compensator

A

adjusts low/high voltage

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37
Q

what current is rectified and unrectified

A

AC- unrectified
DC- rectified

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38
Q

xray tube energy is converted to:

A

mechanical to electrical

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39
Q
  • Most efficient type of electrical generation
  • Employs an armature with three coils
  • 120° apart
  • Each phase of induced current is separated by 120°
A

Three phase generation

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40
Q
  • Convert electrical to mechanical energy
  • Similar components to generators
  • Armature supplied with current
    uses Fleming’s Left-Hand Motor Rule
A

Motors

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41
Q

Synchronous

A

Coils turn at same rate as
armature supplying
current

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42
Q

Asynchronous

A

Variable speed

43
Q

what are the motor types

A

synchronous and asynchronus

44
Q

what waves are least efficient to most efficient

A

-half wave
-full wave
-3phase, 6 pulse
-3phase, 12 pulse
- high frequency

45
Q

what are the types of meters

A

ammeter
voltmeter

46
Q

what meter:
Connected in series
Measures current flow

A

ammeter

47
Q

what meter :

A

Connected in parallel
Measure potential difference between two points in circuit

48
Q

what controls electrical current

A
  • Transformers
  • Autotransformers
  • Capacitors
49
Q

what wave has 1% loss

A

high frequency

50
Q

how much loss is in 3 phase 12 pulse

A

4 percent

51
Q

how much loss is in 3 phase 6 pulse

A

13 percent

52
Q

how much loss is in half and full wave

A

100 percent

53
Q

what wave is the third efficient

A

3 phase 6 pulse

54
Q

motor components

A

-rotor
-stator windings

55
Q

what happens to the voltage and amps in step up and step down

A

step up:
increase in volts, decrease in amps

Step down:
decrease in volts, increase in amps

56
Q

electrical storage energy

A

capacitor

57
Q

is voltage higher or lower in step up

A

higher voltage

58
Q

is voltage higher or lower in step down

A

voltage is lower

59
Q

voltage induced in secondary coil directly related to number of turns in secondary coil

A

transformer law

60
Q

what is the relationship between voltage and amperage in transformer law

A

Induced voltage and amperage are inversely proportional

61
Q

what is the most common and most efficient transformer type

A

shell type

62
Q

transformer types

A

Air Core
Open Core
Closed Core
Shell type

63
Q

what side is the low and high voltage at

A

low voltage- primary side
high voltage - secondary side

64
Q

boiling off electrons

A

thermionic emission

65
Q

need for rectification:

A

xray tube can only operate on direct current

66
Q

process of alernating to direct current

A

rectifier
-full wave more efficient

67
Q

two designs for autotransformer

A

o Primary and secondary coils connected in series
o Single coil on central core

68
Q

three divisions for basic xray circuit

A
  1. Low voltage circuit
  2. High tension circuit
  3. Filament circuit
69
Q
  • Accumulates and stores electrical charge
  • Charged with DC voltage
  • Unit of capacitance
A

capacitors

70
Q
  • Process of changing AC to DC
A

Rectification

71
Q
  • Primitive form of current rectification
  • Performed by x-ray tube which acts as a diode device in the
    circuit
  • X-ray tube not designed to be a diode rectifier
  • Produces a DC waveform that is 50% of full-wave rectification
  • Very inefficient x-ray production and damaging to tube
A

self rectification

72
Q
  • Produces a DC waveform similar to self-rectification
  • Employs single rectifier in circuit
  • Protects x-ray tube from acting as a diode rectifier
    o Protection is marginal
  • Inefficient x-ray production
  • Utilized in very inexpensive x-ray units
    o Veterinary
    o Podiatric
A

Half-Wave Rectification

73
Q

Takes advantage of both phases of alternating current
* Provides only DC to x-ray tube
* Uses at least four rectifiers in a bridge rectification circuit
* Most efficient form of current for x-ray production
o All modern equipment is full-wave rectified

A

Full-Wave Rectification

74
Q

Electrical process of liberating electrons from a wire filament
* Filament is heated to very high temperature, due to its resistance
o Filament is typically tungsten
* “Boiling off” electrons create an electron cloud around filament
* Principle of an incandescent light bulb
* Very important to x-ray tube design

A

thermionic emission

75
Q

what current does the electrons flow in one direction

A

direct current

76
Q

The flow of electrons in an electrical circuit

A

current

77
Q

what current does the electrons move back and forth

A

Alternating current

78
Q

what current does transformers use?

A

Alternating current

79
Q

difference in charge

A

voltage

80
Q

what current does step up and step down transformers function on

A

alternating current

81
Q

what is the rectifier located in between

A

step up and xray tube

82
Q

number of distinct wave cycles

A

phase

83
Q

number of voltage pulses per cycle

A

pulse

84
Q

number of pulses

A

frequency

85
Q

where there is more turns on primary compared to secondary is it step down or step up

A

step up

86
Q

what is the turns ratio

A

N(secondary) / N(primary)

87
Q

first of three transformers in xray circuit

A

autotransformer

88
Q

can increase or decrease voltage and amps
can be step up or step down
small changes
adjustable

A

autotransformer

89
Q

An electrical component that inhibits the flow of current through a circuit
designed to reduce current flow through a circuit
decreases voltage

A

resistors

90
Q

a unit of measure of the degree of resistance between two points of a conductor within a circuit

A

ohms

91
Q

also referred to as intensity and measure of electrical current

A

amperage

92
Q

provides electrical potential /power

A

voltage

93
Q

the resistance of the particles to flow within a circuit

A

ohms

94
Q

the force given to each particle to move

A

voltage

95
Q

all parts or circuit elements are connected in a continous line
any break causes the circuit to fail

A

series

96
Q

its current is able to flow beyond its continuous line , a break in parallel circuit still allows it to function

A

parallel circuit

97
Q

change the voltage (polarity) in an electrical circuit
increase or decrease voltage

A

transformers

98
Q

transformers have three parts:

A

iron core
primary coil (electricity in)
secondary coil (electricity out)

99
Q

polarity of voltage rapidly changes back and forth

A

unrectified

100
Q

electrons flowing in the reverse direction are blocked

A

rectified

101
Q

which rectification is described :
the gap between pulses has no electron flow and the other wave is blocked

A

half wave rectification

102
Q

which rectification is described :
all electrons flow in the same direction
back flowing electrons are not blocked (their polarity is changed so they flow in the same direction)
no gaps between pulses, but wave drops to 0

A

full wave rectification

103
Q

work by self induction
do step up and step down
make only small changes
has only 1 coil around a single coil

A

autotransformer

Exposures II (7 decks)

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