Test 2 Flashcards
1
Q
Type of induction from one wire to another (primary & secondary)
A
Mutual Induction
2
Q
Opposing current induced in the coil of wire itself (autotransformer) A.T.
A
Self Induction
3
Q
What kind of transformer from cathode to anode and why?
A
Step Up Transformer
Because you need more voltage than the power company can supply to propel electrons to anode for kVp
4
Q
What kind of transformer to produce thermionic emission and why
A
Step down transformer
To produce more Amperage (current-mAs)
5
Q
What kind of transformer to supply the cathode and why
A
Step down transformer need more amperage
6
Q
What is Lenz’s Law
A
The induced current flow will be in the opposite direction (opposing) as the action that produces it (moving magnetic field.
7
Q
How much current is induced to flow in the conductor placed in a changing magnetic field depends on…
- strength
- quickly oscillating (changing)
- angle between conductor & field
- # of turns on conductor
A
Farady’s Law
8
Q
What kind of transformer do you need between the cathode and the anode? Why?
A
Step up transformer
need more kV (volts)
9
Q
Voltage goes down amperage goes up
kind of transformer
A
Step down transformer
10
Q
500 primary newtons to 300 secondary newtons
A
Step down transformer
11
Q
When current flow changes direction
A
Magnetic field flips
12
Q
- Battery magnetic field only flows one way.
- No changing magnetic field
- Transformers will not work with this kind of electricity
A
Direct Electricity
13
Q
Gets it’s power from an outlet-power source
A
Primary wire
14
Q
Gets it’s power off a primary magnetic field
A
Secondary Wire
15
Q
- A primary A/C current (pluggin) next to but not touching….
- A secondary A/C wire (not plugged in)
A
Transformer
16
Q
A/C stand for
A
Alternating current
17
Q
- Charge flips
- Electrons flowing through a conductor
A
Magnetic field
18
Q
Charge changes direction
A
Current flow
19
Q
Electrons flowing through a conductor gives you….
A
Magnetic field
20
Q
Bending the conductor concentrates charges in the …..of a conductor
A
Center
21
Q
A coiled conductor is called a….
A
Solenoid
22
Q
Inhibit the flow of electrons
rubber/plastic
A
Insulators
23
Q
Allow electrons to flow
-ease of heat conduction typically equates to ease of electricity conduction
A
Conductors
24
Q
Moving charges are concentrated on the surface of a …..(metal wire)
A
Conductor
25
Moving charges (electrons) are distributed throughout a.....(block of wood)
Non conductor
26
- Study of stationary electrical charges
- Moving on a conductor
- Measured in Coulombs
Electrostatics
27
Attraction/Repulsion inversely proportional to distance between charges and directly proportional to strength of charges.
(same as binding energy)
Coulombs Law
28
Unlike charges do what
Attract
29
Like charges do what
Repulse
30
Relate Energy and Frequency
-Energy and Frequency are DIRECTLY proportional.
-Planks constant of proportionality:
h= 4.15x10(-15) eVs
h= Planks constant
e= hf
Both of the above = c/a=freq.
31
What is the "source" in fluro?
Patient body
32
What is a typical source size?
| "think anode target"
.3 mm
33
What is the "source" in diagnostic imaging?
The Anode/target spot
34
What is a realistic distance at which inverse square law is applicable?
7 x's the source size away
35
The closer you are to the tube the more or less exposure you get?
More
36
If I double my distance from point "A" to point "B" from the x-ray tube what law would I use to calculate my new exposure rate?
Inverse square law
37
What is the formula for the inverse square law?
Old Intensity/New Intensity = New Distance squared/Old Distance squared
38
This applies to a point source...
Inverse square law
39
Some absorption
Some scatter
Some non-interaction
Shades of Gray
40
Items x-rays pass through virtually unimpeded. Appear black on image.
Radiolucent
41
Absorbs lots of x-ray photons looks white on image
Radiopaque
42
2 types of contrast
Radiopaque and Radiolucent
43
Beam that comes out of patient
Remnant Beam
44
Beam that hasn't gotten to the patient coming from the tube
Primary Beam
45
Frequency is measured in...
Hertz
46
Weight and force are measured in...
Newtons
47
Resistance is measured in...
Ohms
48
Electricity is measured in...
Volts
49
Current is measured in...
Amperes
50
The less energy the (blank) photon retains, the greater the change in direction of travel.
(i.e. 90 degrees from patient)
Scatter-Compton interactions
51
Happens IN the patient.
| Photons give up some of their energy to matter and exit in a new direction with reduced energy.
Scatter-Compton interactions
52
X-ray photons that are COMPLETELY absorbed.
| *more likely when incident photon is of relatively LOW energy to start with*
Photo Electric Interactions
53
X-ray and gamma-rays described by...
Energy
54
RF Waves described by...
Frequency
55
Visible light described by...
Wavelength
56
What is Electromagnetic Spectrum
- Covers many orders of magnitude in wavelength.
- Only x and gamma photons have sufficient energy to ionize
- Compare for MRI:
- much longer wavelengths
- lower frequencies
- lower energies
57
Frequency x's wavelength
FW
equal to speed of light
Velocity
58
How many cycles per sec.
Measured in hertz
Velocity/Wavelength
Frequency
59
- The distance from any point on the wave to the same point on the next wave
- Measured in meters
- Velocity/frequency
Wavelength
60
"C"
Frequency x's Wavelength
Equal to velocity
Speed of light
61
Lower kVp has (blank) wave lengths
Longer
62
Higher kVp has (blank) wave lengths
Shorter
63
Speed of light (C)
3 x's 10 (8) m/s
3 x's 10 (10) cm/s
*both above are the same thing*
Electromagnetic Radiation
64
Explain electromagnetic radiation
X and gamma rays travel at the speed of light or not at all...velocity of these photons is constant.
Sine waves represent the travel of these photons with consideration of electric and magnetic fields.
65
The higher the kVp the (blank) absorption
- ie more scatter
- long scale
Less
66
The Lower the kVp the (blank) absorption
- ie less scatter
- short scale
- higher patient exposure
More
67
Photoelectric (PE)
| Short scale contrast
Absorption
68
Absorption is directly or indirectly related to patient exposure
Directly
69
If you have electrons flowing through a conductor you have what
A magnetic field
70
A change in voltage is based on the change or number of turns between what
The primary and secondary wire
71
If current flow changes direction...
The magnetic field flips
72
As voltage goes down, Amperage goes
UP
73
| A coiled conductor is called a...
| Solenoid
74
The greatest concentration of electrons is on the (blank) of the wire.
Greatest curvature
75
Step Up transformer =
Voltage UP
76
Step Down transformer=
Voltage DOWN
77
If one element goes out on THIS kind of circuit, ALL the elements go out
Series
78
If one element goes out on THIS kind of circuit, only THAT element goes out. The current flow has not been disrupted.
Parallel
79
In a Parallel circuit WHAT is constant
Voltage
80
In a Series circuit WHAT is constant
Amperage
81
Average US everyday appliances run on how much voltage?
110
82
To get from an Alternating electrical Current (A/C) you have to do WHAT to get a full current
Rectification
83
The number of positive peaks (impulses) per second in the US (60 Hz) for a
Single Phase, Half Wave rectified
1/120th Hz
84
The number of positive peaks (impulses) per second in the US (60 Hz) for a
Single phase, Full Wave rectified
1/60th Hz
85
The number or positive peaks (impulses) per second in the US (60 Hz) for a
Triple Phase, Full Wave rectified
High Frequency Voltage
86
What kind of flow comes from the power company?
A/C
87
What is the advantage of using a Single phase 1/2 wave: suppressing the negative 1/2 cycle, effect have on the Tube?
Reduces the amount of heat, causing less damage to the tube
| Still only getting x-rays half of the time
88
What does a Single phase, Full wave: inverting the negative 1/2 cycle, effect have on the tube/x-rays?
The Cathode is heated the whole time (pulsating direct current)
89
A 3 phase, 6 pulse or 3 phase, 12 pulse rectified current produces what?
Near direct current (eliminating the variations in efficiency)
90
What is takes to push electrons through is measured in....
Power
91
The formula for power is...
P=IV
| V=IR or P=I(IR) or P=(Isquared)(R
92
You can calculate power by knowing any of the following two:
Voltage, Amperage, Resistance
93
Stored (source of) electric energy
| and where might we as x-ray techs use this
Battery
| -Portable machine
94
Supplied with current to Produce Mechanical energy (motion) and where might we as x-ray techs use this
Motor
| -Physical activity
95
Mechanical energy (motion) Produces Electrical Energy (amperage) and example of what is a generator
Generator
| -Hamster in a wheel
96
A coiled conductor (wire)
Solenoid
97
A coiled conductor with iron core
| which intensifies the magnetic fields
Electromagnet
98
Current is induces to flow in a conductor that is in a moving (changing) magnetic field (so alternating current is a prerequisite)
Induction
99
Faraday's Law says...
How much current is induced to flow in a conductor placed in a changing magnetic field depends on...
- How STRONG the magnetic field is
- How QUICKLY the magnetic field is oscillating (changing)
- What the angle between the conductor and the field is
- How MANY TURNS are on the conductor (ie 300 or 200, etc)
100
Lens's Law says...
The induced current flow will be in the opposite direction ("opposing") as the action that produces it (moving magnetic fields)
101
Self Induction is induced by using a/an what kind of transformer
Autotransformer
102
Mutual induction is induced by using a/an what kind of transformer
Primary & Secondary
103
Rectification (conversion from AC to near DC) must come before or after all transformers in the x-ray tube?
After
104
How many transformers are in the x-ray tube before rectification occurs?
3
105
Change in (blank) from primary to secondary wire will be (blank) proportional to the ratio of coils/turns.
Voltage
| Directly
106
Change in (blank) from primary to secondary is (blank) proportional to ratio of coils
Amperage
| Inversely
107
50,000 turns secondary; 1000 turns primary
- What kind of transformer is it?
- Will voltage go up or down? How much?
- Will Amperage go up or down? How much?
- Step up
- Voltage up 50 x's
- Amperage down by 1/50th
108
400 turns secondary 16,000 turns primary
- What kind of transformer is it?
- Will voltage go up or down? How much?
- Will amperage go up or down? How much?
- Step down
- Voltage goes down 1/40th
- Amperage goes up 40 x's
109
Describe and Autotransformer
Has only one wire with variable taps and is a self-inducing transformer
110
Where does voltage (kVp) selection occur?
Autotransformer
111
Induction motor does what
Makes the Anode spin inside a vacuum
112
A high voltage Step Up transformer gets us from 220 V coming in from the wall to...
70-110 KILOvolts for x-ray imaging
113
What measures power coming in and makes adjustments to keep it consistent before it gets to the Autotransformer
Line voltage Compensation Autotransformer
114
What are the 3 formulas for the speed of light
- 3x10 (8)
- 3x10 (10cm)
- 186,000 miles per second
115
Velocity of gamma and x-rays is...
constant
116
Cycles per second is also
hertz
117
Frequency and wavelength are (blank) related
inversely
118
Exposure rate, intensity, MR all indicate...
Inverse square law
119
Energy of a photon...
Planks constant
| e=hf
120
Columbs Law
As distance between charges increases, the force decreases
| *magnets*
121
Turns ratio
number of turns secondary/ over number of turns primary
