Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

Radiologic Physics > Chapter 4 > Flashcards

Chapter 4 Flashcards

1
Q

Electrostatics

A

The study of electrostatic charges

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

Electrodynamics

A

The study of electric charges in motion

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

How many electrons equals 1 coulomb?

A

6.25x10^18 electrons

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What makes a good conduction? Example?

A

Movement of free electrons

Copper and gold

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are examples of insulators?

A

Glass, plastic, wood

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

Principles of Electrostatic

A
  1. Like charges repel, unlike charges attract
  2. Electric charges reside on the outside external surfaces of conductors
  3. Coulomb’s Low
  4. Concentration of charges always accumulate more on a curved surface
  5. Only electrons are free to move across conductors
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

What is Coulomb’s Law?

A

The farther away 2 charges are, the less their force. The closer they are, the stronger their force

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What is electric potential?

A

Ability to do do work due to a separation of charges

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What is current?

A

Flow of electrons through a conductor

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is resistance?

A

Property that resists current or flow, makes it more difficult

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

How is electric potential measured?

A

Volts

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What is a volt?

A

The potential difference that will maintain 1 current of 1 amp in a circuit with a resistance of 1 ohm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

Ohm’s Law

A

V = IR

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

kVp determines:

A

Quality/penetration
Subject contrast
Influences contrast digitally

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What controls subject contrast in production?

A

kVp

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What controls contrast in digital imaging processing?

A

LUT

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
17
Q

How is current measured?

A

Amps - named after Andre Ampere

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
18
Q

How do electrons travel in xray tube?

A

Jump the gap between cathode to anode

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
19
Q

What is AC?

A

Current of both positive and negative sine wave. Continuously chages direction in cycles.

Type of circuitry right before the tube

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
20
Q

What is AC measurement in USA?

A

60 cycles per second/60 hz

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
21
Q

What is DC?

A

Current that only flows in one direction

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
22
Q

How is resistance measured?

A

Ohms

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
23
Q

How does area size affect resistance?

A

Larger area has less resistance.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
24
Q

What temperatue is better for conducting of electricty?

A

Low

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
25
Q

In a series circuit, what is the same across each resistor?

A

Current

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
26
Q

In a parallel circut, what is the same across each resistor?

A

Voltage

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
27
Q

What kind of circuit will not conduct electricity?

A

Open

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
28
Q

What kind of circuit will conduct electricity?

A

Closed

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
29
Q

How does a rectifier work?

A

Turns AC to DC

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
30
Q

What are diodes?

A

A one way valve that help turn AC to DC in the rectifier

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
31
Q

The mA selector is known as a

A

Rheostat

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
32
Q

What is a rheostat?

A

A variable resistor (changes the resistance)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
33
Q

What is a transfomer?

A

Device that changes voltage and current

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
34
Q

How does a step-up transfomer work?

A

Change voltage to high and current to low

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
35
Q

How does a step-down transfomer work?

A

Changes voltage to low and current to high

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
36
Q

What is electromagnetism?

A

Electricity and magnetism together in the same phenomenon

37
Q

In magnets, orbital electrons predominately spin in what direction?

A

The same direction

38
Q

What is flux?

A

Lines of force in space around a magnetic field

39
Q

How does flux travel?

A

Inside - south pole to north pole

Outside - north pole to south pole

40
Q

Lines of flux in the same direction:

A

repel each other

41
Q

Lines of the flux in the opposite direction:

A

attract each other

42
Q

How are magnetic fields distorted?

A

By other magnetic materials, but not by nonmagnetic material

43
Q

Force of attraction or repulsion of a magnet depends on what?

A

Strength and distance

44
Q

What are nonmagnetic materials and how are they attracted to magnets?

A

Wood, glass, plastic

Not attracted at all

45
Q

What are diamagnetic materials and how are they attracted to magnets?

A

Water, gold

Slightly repelled

46
Q

What are paramagnetic materials and how are they attracted to magnets?

A

Platinum, gadolinium

Slightly attracted

47
Q

What are ferromagnetic materials and how are they attracted to magnets?

A

Iron, cobalt, nickel

Strongly attracted

48
Q

What is a solenoid?

A

Conductor fashioned into a coil

49
Q

What is an electromagnet?

A

Iron core in a solenoid

50
Q

What 2 forms of current induction are used in x-rays?

A

Mutual induction and self-induction

51
Q

What is mutual induction?

A

Uses 2 solenoids. The current switches direction in cycles - creating AC current

52
Q

What is self-induction?

A

Only 1 solenoid. As the cycles create back and forth “cuts” across the single coil, it induses a constant secondary current (autotransfomer)

53
Q

What do electric generators do?

A

Convert mechanical energy into electrical energy

54
Q

What do electric motors do?

A

Covert electrical energy into mechanical energy

55
Q

What is the most common type of transformer?

A

Shell core

56
Q

3 Circuits in Xray

A

Primary, secondary, filament

57
Q

What comes into the primary circuit?

A

220 Volts

58
Q

What adjusts the voltage to be 220 Volts?

A

Line voltage compensator

59
Q

What are the 3 types of times located in the primary circuit?

A

Electronic timer
mAs timer
AEC timer

60
Q

What is included in the primary circuit?

A

Main power switch
Fuses
Line meter
Emergency stop
Line voltage compensator
Autotransfomer
kVp major
kVp minor
Timing switch exposure switch
kVp meter

61
Q

What is included in the secondary circuit?

A

mA meter
Rectifiers
Secondary coil of step up transfomer
Tube
Ground

62
Q

What is ripple?

A

Efficiency of turning AC to DC.

63
Q

How does the secondary circuit work?

A

Primary coil of the step up transfomer gets exactly 220V, it then steps it up to the secondary coil.

It creates the kVp you choose

kVp goes through a rectifier. Turns AC to DC. Zaps electrons from cathode side to anode

64
Q

What are the voltage ripple precentages for single phase?

A

100%

65
Q

What are the voltage ripple percentages for 3 phase?

A

6 pulses - 13%
12 pulses - 4%
high frequency - <1%

66
Q

A single phase machine uses higher or lower kVp than a 3 phase?

A

Higher - does not expose patient to a different dose of radiation

67
Q

What is included in the filament circuit?

A

mA selector/rheostat, focal spot selector, step down transfomer

68
Q

What happens in the filament circuit?

A

Rheostat is controlled by mA selector on console

This controls the current that is applied to the filament and directly related to the number of electrons boiled off

The step down transfomer decreases voltage and increases current. Turns amperage to mA

mA goes to the mA meter and the filament circuitry in the cathode

69
Q

What happens in the primary circuit?

A

Voltage comes in and gets measured by the line meter. Compensator adjusts voltage to be exaclty 220V

Autotransfromer adjusts its coils up and down to deliver voltage to both step up and step down

70
Q

How does mA affect resistance and the electron beam?

A

High mA uses large filament which creates more electrons and a larger beam.

A larger beam has less resistance (needs room to expand)

71
Q

How many volts are in 1 kV

A

1000 volts = 1 kV

72
Q

How many amps are in 1 mA

A

.001 amps = 1mA

73
Q

What is a way to check your math for total ohms in parallel circuit?

A

Lowest ohms is always almost half of the total total resistance

74
Q

How do you figure out total resistance in a parallel circuit?

A

1
___________________________
(1/R1)+(1/R2)+(1/R3)+(1/R4)

75
Q

How do you figure out total resistance in a series circuit?

A

Add up ohms
R1+R2+R3+R4

76
Q

What is the turns ratio?

A

Secondary turns:Primary turns

77
Q

What is the transformer formula?

A

Vs = Ts = Ip
____________
Vp = Tp = Is

78
Q

What is the magnetic domain?

A

Groups of similary aligned atoms formed by dipoles (atomic magnets)

79
Q

What happens when magnetic material is placed in a magnetic field?

A

The domains will align with the external field. It then magnetizes the material creating a magnet

80
Q

Shell-core has the least amount of:

A

Leakage flux

81
Q

What is the efficiency rate of a shell-core transfromer?

A

95% efficient, 5% non efficient (leakage flux)

82
Q

How many electrons does the small filament produce compared to large?

A

Small - 1x
Large - 4x

83
Q

What does the receptor exposure control do?

A

Ability to change the rate of intensity

84
Q

How many volts usually goes to the filament circuit?

A

8-12 volts

85
Q

What type of generator is not used in the medical diagnostic realm?

A

High frequency

86
Q

What is the highest efficiency generator we use in X-ray?

A

Three phase, 12 pulse

87
Q

When using AEC, what mAs should the backup timer be set for?

A

150%

88
Q

Equation for Power

A

P=IV or
P=I^2R

Radiologic Physics (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2025 Bold Learning Solutions. Terms and Conditions