EMR Flashcards
1
Q
is supplied to the X-ray imaging system to be converted into electromagnetic energy
A
Electric Energy
2
Q
- is the set of phenomena associated with the presence and motion of matter that has a property of electric charge.
- is the presence and flow (movement) of charge.
- is sometimes used to mean “electrical”.
A
Electricity
3
Q
- is the basic property of matter carries by some elementary particles
- comes into two types: positive (+) and negative (-)
A
Electric Charge
4
Q
are the smallest units of electric charge
A
Electrons and Protons
5
Q
has one unit of negative electric charge
A
Electron
6
Q
has one unit of positive charge
A
Proton
7
Q
_____ charges repel
A
Like
8
Q
_____ charges attract
A
Unlike
9
Q
Like charges ______
A
Repel
10
Q
Unlike charges ______
A
Attract
11
Q
What is the unit of charge?
A
Coulomb
12
Q
The unit of charge is Coulomb which was named after _______________ (eminent French Physicist)
A
Charles-Augustin de Coulomb
13
Q
1 Coulomb = _________ electron charges
A
6.24x10^18
14
Q
The smallest unit of “free” charge known in nature is the charge of an electron or proton which has a magnitude of ___________
A
1.602x10^-19C
15
Q
Electric charges associated with electrons and protons have the (a) ______ magnitude but (b) ______ signs
A
(a) same, (b) opposite
16
Q
Law which states that “the electrical force between two charged objects is directly proportional to the product of the quantity of charge on the objects and inversely proportional to the square of the separation distance between the two objects”.
A
Coulomb’s Law
17
Q
what is the value of Coulomb constant (k)?
A
9x10^9Nm^2/C^2
18
Q
- is a force that acts at a distance, even when objects are not in contact with one another
- The action at a distance means that one charge creates a field which in turn acts on the other charge
A
Electrostatic Force
19
Q
provides a convenient graphical presentation of the electric field in space
A
Electric Field Lines
20
Q
The direction of the field lines is radially outward for a ________ charge
A
positive
21
Q
The direction of the field lines is radially inward for a ______ charge
A
negative
22
Q
The direction of the field lines is radially _________ for a positive charge
A
outward
23
Q
The direction of the field lines is radially _________ for a negative charge
A
inward
24
Q
What are the three ways for a neutral object to be charged?
A
- Friction
- Conduction
- Induction
25
- Occurs when two different materials rub against each other causing the transfer of electrons
- is the opposing force which acts in the opposite direction of the movement of the upper body
Friction
26
Occurs when a neutral object is placed in contact with an already-charged object
Conduction
27
- a charged object is brought near but not touched to a neutral conducting object.
- not in contact
- The presence of a charged object near a neutral conductor will force (or induce) electrons within the conductor to move.
Induction
28
What are the four electric states of matter?
1. Superconductor
2. Conductor
3. Semiconductor
4. Insulator
29
- no voltage needed
- No resistance to electron flow, no electric potential required, and must be very cold
- The critical temperature usually between absolute zero and 10 Kelvin (-273 Celsius and -263 Celsius or as high as 125 Kelvin (-148 Celsius)
Superconductor
30
are used in machines for nuclear magnetic resonance (NMR) in hospitals and in the orientation of the beam of a particle accelerator.
Superconducting Magnets
31
- application of voltage is required to the flow of electron
- includes copper, aluminum
Conductor
32
is a substance in which electrical charge carriers (usually electrons), move easily from atom to atom with the application of voltage
Electric Conductor
33
- does not allow the flow of electrons
- is a material that does not conduct electrical current
- these materials include paper, plastic, rubber, and glass
Insulator
34
- A solid substance that has a conductivity between that of an insulator and that of most metals
- devices made of ___________, notably silicon, are essential components of most electronic circuits.
Semiconductor
35
- is defined as the electric potential energy, U , per unit charge
- ____ = U/q
- sometimes referred to as the voltage
Electric Potential (V)
36
The higher the (a) _________, the (b) __________ the potential to do work
(a) voltage, (b) greater
37
- electric potential
- is an electromotive force or potential difference expressed in volts
- 1 V = 1 J/C (Joule per Coulomb)
Voltage
38
The Volt unit is named after (a) ______________, an Italian physicist who invented an (b) __________
(a) Alessandro Volta, (b) electric battery
39
- is the rate of flow of electrons in a wire.
- SI Unit is Ampere (A)
- 1 A = 1 C/s (Coulomb per seconds)
Electric Current
40
Ampere was named after _________________________
Andre Marie Ampere
41
- is a measure of opposition to the flow of electric current
- The inverse is electrical conductance
- SI unit is Ohm
Electric Resistance
42
Ohm was named after a German physicist and mathematician _____________
Georg Simon Ohm
43
Law which states “The amount of electric current through a metal conductor in a circuit is directly proportional to the voltage applied across it and inversely proportional to the resistance”
Ohm’s Law
44
- is a measure of energy per unit time.
- gives the rate of energy consumption or production.
- The units for _________ are generally watts (W).
Power
45
is measured in kilowatt-hours, kWh.
Electric Energy
46
- is a fundamental property of some forms of matter.
- Some objects are known to attract iron fillings. These phenomena is called __________.
Magnetism
47
A charge particle in motion also creates ____________.
magnetic field
48
In radiologic sciences, understanding magnetism is important in ______________________ which uses powerful magnetic fields to create images of the human body.
magnetic resonance imaging
49
- is a vector field that describes the magnetic influence of electrical currents and magnetized materials.
- is also created by a moving electric charge.
Magnetic Field
50
What is the SI Unit of magnetic field (B) is ________
Tesla (T)
51
Magnetic field (B) is also measured in ________
Gauss (G)
52
Magnetic field is (a) ____________ (magnetic dipole). It has a (b) ____________ and (c) __________ pole.
(a) dipolar, (b) north, (c) south
53
are regions at the end of the magnet where the magnetic field are strongest.
Poles
54
Law of (a) ____________: Like magnetic poles (b) __________ and unlike magnetic poles (c) _________.
(a) Magnetism, (b) repel, (c) attract
55
- is a region created by the accumulation of many atomic magnets with their dipoles aligned.
- This means that the individual magnetic moments of the atoms are aligned with one another, and they point in the same direction.
Magnetic Domain
56
(a) ___________ is a consequence of the electromagnetic force,
one of the four fundamental forces of nature, and is caused by the _____________.
(a) Magnetic Force, (b) motion of charges
57
- As moving charges create magnetic fields, so they experience forces from magnetic fields generated by other materials. The magnitude of the force experienced by a particle traveling in a magnetic field depends on the charge of the particle (q), the velocity of the particle(v), the strength of the field(B), and, importantly, the angle between their relative directions(θ).
Lorentz Force
58
The magnetic force is described by the _____________
Lorentz Force Law
59
Type of magnet which Earth is the common example.
Natural Magnets
60
- Type of magnet which is usually made of iron.
- Made by aligning their domains in the field of an electromagnet.
Permanent Magnets
61
Type of magnet which consists of wire wrapped around an iron core.
Electromagnets
62
Type of magnet which materials that are unaffected by magnetic field.
Nonmagnetic
63
- Type of magnet which materials that are weakly repelled by magnetic fields.
- They cannot be artificially magnetized, and they are not attracted to a magnet.
Diamagnetic
64
- Type of magnet which materials that lie somewhere between ferromagnetic and nonmagnetic.
- They arr slightly attracted to a magnet and loosely influence by an external magnetic field.
Paramagnetic
65
Type of magnet which is strongly attracted to magnets or magnetic materials and usually can be permanently magnetized by exposure to a magnetic field.
Ferromagnetic
66
- is a process where a magnetic field is created by introducing a current into the conductor or by producing electricity with changing magnetic field.
- is a branch of Physics that deals with the electromagnetic force that occurs between electrically charged particles.
Electromagnetism
67
- is a type of physical interaction that occurs between electrically charged particles.
- is one of the four fundamental forces of nature.
- acts between charged particles and is the combination of all magnetic and electrical forces.
- can be attractive or repulsive.
Electromagnetic Force (EMF)
68
A coil of wire is called a ______.
solenoid
69
is a current-carrying wire wrapped around an iron core, which intensified the induced magnetic field.
Electromagnet
70
- He discovered that electric currents create magnetic fields.
- He is a Danish physicist and chemist
Hans Christian Ørsted
71
This was the first connection found between electricity and magnetism.
Electromagnetic Induction
72
In 1831, _______________ formulated two laws on the bases of his experiments.
Michael Faraday
73
The ______ Law of Induction states that “Whenever a conductor are placed in a varying magnetic field, an electromotive force (emf) is induced. If the conductor circuit is closed, a current is induced which is called induced current.”
First Law
74
The ________ Law of Induction states that “The magnitude of the induced emf in a coil is equal to the rate of change of flux that linkages with the coil.”
Second
75
is the product of the number of turns in the coil and the flux associated with the coil.
Flux Linkage
76
He proposes a Theory of Electromagnetic Field which has something to do with the space in the neighborhood of the electric or magnetic bodies
James Clerk Maxwell
77
is that part of space which contains and surrounds bodies in electric or magnetic conditions (Maxwell, 1864)
Electromagnetic Field
78
are waves that are created as a result of vibrations between an electric field and a magnetic field.
Electromagnetic Waves (EM Waves)
79
is a form of energy that is produced by oscillating electric and magnetic disturbance, or by the movement of electrically charged particles traveling through a vacuum or matter.
Electromagnetic Energy
80
The (a) _______ field and (b) _________ field of an electromagnetic wave are (c) ____________ (at right angles) to each other. They are also perpendicular to the direction of the (d) _________.
(a) electric, (b) magnetic, (c) perpendicular, (d) EM wave
81
What is the value of the speed of light?
3x10^8 meters/sec
