Physics Flashcards
Ohm
SI unit of resistance
Watts
SI unit of electrical power
Comptons affect
Secondary radiation formed by high energy photons striking a electron in its outer shell also know as scattered radiation producing energy radiation
Photon
Is a little piece of energy floating in space
Amperes
Is a the SI unit measurement for electrical current
Volts
sI unit of electromotive force
Bremsstrahlung or breaking radiation
Produced in the x Ray tube . The action of shooting electrons from the cathode to the anode the sudden deceleration produces x Rays with 99% heat and 1% radiation
Coulombs
The unit of measurement for electrical charge ( do not confuse with current)
Milliamperage meter
This measures the tube current
Kvp
Determines the quality of the X-ray beam
More Kvp say 120 vs 70 produces stronger more penetrating x Rays in less time
Less Kvp produces longer weaker x Rays
mAs
mA (50,100,150,200 dial on machine) and S= seconds/time = the combination of these two control the quantity of the electrons produced
Atom
Smallest unit that matter can be divided into while still maintaining its unique properties
Bohr model
Devised by Neil’s Bohr set up like a solar system model with a central sun representing the nucleus and surrounding planets representing the electrons
Proton
Holds a positive charge is located in the nucleus
Neutron
Holds No charge and is located in the nucleus
Electron
Holds a negative charge smaller the the proton .
1 atom is a chemical element
2 or more atoms make up a molecule
2 or more Molecules make up a compound
Atomic number
Represents the letter Z . It os the total number of protons in the atom
Atomic mass
Representing the letter A it is the total number of protons and neutrons in the atom
Isotopes
An atom which has the correct number of protons but a different number of neutrons
Ions
An atom becomes an ion when it losses or gains a electron .
Ionization
This is the process of adding or subtracting a electron from a atom
Electrons
Electrons hold the same charge with means they are all negative
Neutral atoms
A chemically neutral atom consists of an equal amount of protons and electrons .
Electrons are bound
To the atom by the amount of electrons binding energy EBE
EBE electric binding energy
This corresponds to energy levels . The closer the the lectern is to the nucleus the more EBE it exhibits. In otherwise the less likely the electron is to leave its orbital or be lost .
Energy levels , called shells
K,L,M,N,O,P,Q,R,S
Each level is set as to how many electrons may be in that particular energy shell.
Energy shell numbers
k-2 L-8 M-18 N-32 O-50 P-72 Q-98
Rule of octet
States that the outer shell aka the valance shell aka electrons can only hold a max of 8 electrons
Matter
Anything that occupies space
3 forms of matter
Liquid . Solid , gas
Energy
Is the ability to do work
Types of energy
Kinetic- energy in motion
Potential - stored energy
Electricity
Defined as the absence or excess of electrons
Types of electric Current
DC- electrons move in one direction one way
AC- current moves in an alternating cycle . If you put them together you do not get a band
Magnetism
The ability of a substance to attract iron like substances .
Law of magnetism
The same charges or poles will repel each other while the unlike or poles will attract .
Electro magnetic spectrum wavelength
Low frequency, long wavelength
Radio
Microwave
Infrared
Visible
High frequency, short wavelength
Ultraviolet
X-Ray
Gamma ray
Electromagnetic radiation
3 types of ionizing radiation. We should be concert with 2
Compton effect medium energy ejects from orbit and creates a weaker photon which may also leave the pt to create scatter or radio graphic fog
Photoelectric - low energy ejects an electron from orbit
X Rays are dangerous because ….
1) Give off light . Aka light shit up
2) Undergo biological changes (burns , DNA changes, loss of hair , genetic mutations in future generations
3) produce scatter radiation
X Ray properties
1) travel in a straight line they can’t chase you around the corner
2) exhibit the same characteristics of waves or particles
3) cause certain materials to give of light
The tube components
A vacuum to prevent electrons from hitting the other molecules mainly air
Cathode
Is the Source of electron (where they are produced.
Easy way of remembering cathode makes electrons
Focusing cup
Where the filaments are contained. So remember when we apply power the electrons start to form on the filament.
Thermionic emissions or boiling off
Current is what is applied to the filament to create the electrons
Dual filaments
More modern machines may have two filaments one small for little anatomy parts (hands,feet) and one for large body parts ( chest,spine )
Anode
Made of tungsten. This is what the electrons hit to produce the primary radiation (bremsstrahlung)
Rotating anode
Which is most commonly used for radiography because it allows for greater heat dissipation
Stationary anode
Which is most used in dental radiography
Target
The area of the anode which is struck by the electron beam
Actual focal spot
The electron beam before striking the anode (bigger area)
Effective focal spot
The beam that is projected toward the pt (smaller than the actual focal spot)
The size of the effective focal spot is determined by
1) the angle of the anode (angle the bigger area/beam)
2) filaments larger filament = larger area/beam,smaller filament =smaller area beam
Thermionic emissions (boiling off)
Electrons are created at the filaments when the filaments is heated by the high current . Think of boiling water as the water heats up or produces more bubbles
Tube rating charts
Determines the safety of an exposure. Remember find the intersection on the chart of the point is below then it is safe exposure. If it is above the intersection then it is an unsafe exposure for the tube
