Basic Physics Flashcards
energy of pos.
potential energy
energy of motion
kinetic
energy from chem reaction
chem energy
energy from movement of e-‘s
electrical energy
heat energy from movement of atoms
thermal energy
energy resulting from nucleus of atom
nuclear energy
energy that is emitted/transferred through matter
electromagnetic energy
electromagnetic rad that is able to remove an e- from atom
ionizing rad
how fast an object is moving
velocity
rate of change of speed per unit of T
acceleration
force applied on an object over a distance
work
rate of doing work
power
power is measured in?
watts
what contains most of the mass of an atom?
nucleus
represented by A
atomic mass
of p+’s plus # of n0’s
atomic mass (A)
of p+’s in nucleus
Z
what determines the chem. element?
Z
atoms w same # of p+’s but diff # of n0’s
isotopes
force that holds e-‘s in orbit around the nucleus
electron-binding energy
alpha particles are similar to what? and contain what?
He nucleus; 2 p+’s & 2 n0’s
what are beta particles?
particulate rad that is e- like & emitted from nucleus of radioactive atom
a bundle of photon energy is called a?
quantum
frequency is measured in?
Hz
c in mi/s?
186,000 mi/s
origin of gamma rays?
nucleus of radioactive atoms
3 methods of electrification?
friction, contact & induction
material that allows the free flow of e-‘s
conductor
object that prohibits the flow of e-‘s
insulator
movement of e-‘s along a conductor/pathway (electrical circuit)
electrical current
electrical current is measured in?
amperes
measured in volts; force w which e-‘s move in an electrical circuit
electromotive force (EMF)
material that may act as an insulator or conductor under diff conditions
semiconductor
measured in ohms
electrical resistance
Ohm’s law
V=IR
path along which e-‘s flow; may be wired as series/II circuits
electrical circuits
representation of e- flow as AC
sine wave
what can magnetize a ferromagnetic material, like iron?
magnetic field
every magnet has a ______ & a _______
N & S pole
a coiled conductor (i.e. wire), through which an electrical current is flowing, has what?
overlapping magnetic fields
stacks fo wire coil through which electrical current flows, creating overlapping force field lines; a magnetic field is concentrated through the center of the coil
solenoid
solenoid w an Fe core that concentrates the magnetic field
electromagnet
process of causing an electrical current to flow in a conductor when it is placed w/in the magnetic field of another conductor
electromagnetic induction
opposing V created in a conductor by passing AC through it
self-induction
inducing current flow in a secondary coil by varying the current flow through a primary coil
mutual induction
device that converts mech. energy to electrical energy; usual output is AC
electrical generator
simplest type of current; V (& accompanying current) flow as a sine wave
single-phase, 2-pulse AC
3-phase, 6-pulse waveforms contain ____ pulses/sec
360
3-phase, 12-pulse waveforms contain ____ pulses/sec
720
what produces thousands of Hz’s of electricity?
high-frequency generator
device that converts electrical energy to mech. energy
electrical motor
what requires an AC?
transformer (mutual induction)
transformer that +’s V from primary to secondary coil & -‘s current in same proportion
step-up transformer
what is used in the XR circuit to + the V to the kV level for XR production
step-up transformer
transformer that -‘s V from primary to secondary coil & +’s current in same proportion
step-down transformer
what is used in the filament portion of XR circuit to + current flow to cathode?
step-down transformer
transformer that contains an Fe core & a single winding of wire
autotransformer
what is used in the XR circuit to provide a small + in V before the step-up transformer
autotransformer
kVp settings are made at the?
autotransformer
process of changing AC to DC
rectification
what keeps the incoming V adjusted to the proper value of 220 V?
line voltage compensator
3 conditions necessary for XR production
- e- source, 2. e- acceleration, 3. sudden stop of e- against target material
what is aka the variable transformer?
autotransformer
what is the source for selecting kVp?
autotransformer
secondary turns are selected by the tech using the?
kVp selector
what boosts the V to the kVp selected?
high-V step-up transformer
________ in the XR circuit indicates the V that is selected
prereading voltmeter
where is the pre reading voltmeter located?
btw the autotransformer & the high-voltage step-up transformer
what is used to regulate the duration of XR exposure?
timer
where is the mAs timer located?
after the secondary coil of the high-voltage step-up transformer
what measures the total tube current?
mAs timer
what provides the safest tube current in the shortest T possible?
mAs timer
what is microprocessor controlled and contained in most rad equipment?
electronic timer
what is used to provide consistency of rad quality
auto exposure control (AEC)
AEC relies on positioning skills bc?
the part must be accurately positioned over ionization sensors
what consists of a flat ionization chamber btw the pt & IR?
AEC
the level of ionization is ______ proportional to the density that will appear on the img
directly
what 2 things does the backup timer protect?
the pt from overexposure, and the tube from overheating
what is the shortest T w an AEC?
1 ms (0.001 sec)
modern generator that takes advtg of extremely short T capabilities & tube heat-loading potential
falling load generator
w falling load generator, XR tube current starts @ the ____ level possible for the 1st portion of the exposure
highest
falling load generators always use what to obtain a given mAs?
the shortest T possible
disadvantage of falling load generator?
exams where long exposure T’s needed (orthostatic breathing)
what determines how much the V is stepped up?
turns ratio
the greater the turns ratio, the ____ the resulting kV (step-up transformer)
higher
formula for turns ratio?
Ns/Np
XR tube requires _____ to operate properly
DC
solid-state semiconductor diodes are what?
rectifiers (convert AC to DC)
rectifiers consist of?
silicon-based n-type & p-type semiconductors
where is the rectifier located?
btw the step-up transformer & the XR tube
single-phase results in what % voltage ripple?
100%
how many diodes provides full-wave rectification for single-phase generators?
4
how many diodes provides full-wave rectification for three-phase generators?
6 or 12 diodes
when 3-phase current is used, voltage ______________ during exposure
never drops to 0
voltage ripple for 3-phase, 6-pulse?
13%
voltage ripple for 3-phase, 12-pulse?
4%
voltage ripple for high-frequency?
1%
how much voltage is actually used in a 3-phase, 12-pulse generator?
96% of kVp set
which waveforms produce higher average photon energy?
3-phase, full-wave rectified waveforms (35% higher for 3-phase, 6-pulse & 41% higher for 3-phase, 12-pulse)
what measures the tube current?
mA meter
where is mA meter located?
btw rectifier & XR tube
mA control provides V from autotransformer to?
step-down transformer
what -‘s V & +’s current to heat the filament?
step-down transformer
what is the neg electrode in the XR tube?
cathode
cathode contains how many filaments?
2 (sm & lg)
over time, what leads to tube failure?
filaments vaporize & coat the inner surface of XR tube w tungsten
what is it called when during an XR exposure, 1 filament is heated to a level that causes e-‘s to be “boiled off” to prepare for XR production
thermionic emission
what surrounds the filaments in the cathode?
the focusing cup
the focusing cup has what applied to concentrate the e-‘s boiling off the filaments into a narrow stream toward target?
neg. charge
what is the pos. electrode in the XR tube?
anode
rotation of the anode target allows greater what?
heat dissipation
e-‘s strike the target on the?
focal track/spot
focal track/spot is beveled, producing the?
target angle
the larger the actual focal spot, the greater the _____ _____
heat capacity
the smaller the effective focal spot, the greater the?
img sharpness
glass envelope has a vacuum so e-‘s from filament don’t what?
collide w atoms of gas
what is in the glass envelope that allows XRs to escape?
tube window
indicates the kVp that will flow through the XR tube during exposure
pre-reading voltmeter
regulates duration of XR exposure
timer
what is placed btw pt & IR
AEC
what provides extremely short exposure T’s by taking advtg of tube heat-loading potential
falling load generator
what is the high-V transformer?
step-up
what contains the filaments, the source of e-‘s for exposure
cathode
what consists of the rotor & exposure button
exposure switch
what encases tube , Al lined w Pb?
tube housing
which wavelengths are more penetrating?
short
what removes long wavelength rays?
beam filtration
calculation of the total heat produced during an XR exposure
heat units
digi-fluoro usually eliminates what?
postprocedure “overhead” img’s
smallest particle of an element that retains it’s characteristics of the element?
atom
in digi-fluoro, the img must be turned into digital form by what device?
analog-to-digital converter
XRs travel in bundles of energy called
photons
atomic mass?
p+’s plus # n0’s
what’s used to ensure consistency of rad quality from one exposure to the next?
AEC
when a predetermined level of ionization reaches ionization chamber, the machine?
terminates exposure
what type of XR machine uses a continually decreasing mA for the shortest T’s possible?
falling load generator
what type of current is needed for proper operation of XR tube?
DC
outer shell of an atom can contain no more than 8 e-‘s
octet rule
He nuclei & beta particles are examples of?
particulate radiation
electromagnetic radiation travels in ______ along _______
waves; straight path
speed that XRs travel?
speed of light, 186,000 miles/second
waves of rad are called
sine waves
distance from peak to peak of sine wave
wavelength
of waves passing a point per unit T
frequency
wavelength & frequency are ______ proportional
inversely
XR beam changes as it travels through the pt is called
attenuation
I of rad is inversely proportional to the square of D btw the rad source & pt
inverse square law
as rad strikes matter the energy is transferred to the atoms according to?
the law of conservation of energy
a ____________ always surrounds an electrical charge in motion
magnetic field
current flows back and forth in
AC
what allows the free flow of e-‘s?
conductors
unit of potential diff
volt
path of electrical current
circuit
process of causing an electrical current to flow in a conductor when it is placed in the magnetic field of another conductor?
electromagnetic induction
self-induction is used in the operation of what?
autotransformer
strength of the magnetic field in a transformer is increased by
coiling the wires & letting their magnetic fields overlap
electricity is supplied to the imaging dept by a
generator
electricity provided to the rad dept.
60 Hz AC
electricity provided to the rad dept. operates at
120 pulses per sec
primary advtg of 3-phase power is that
V never drops to 0
a variable transformer that is used to select kVp for the XR circuit is?
autotransformer
what transformer boosts the V to kV?
step-up
V in XR machine kept constant by
line voltage compensator
where does thermionic emission occur?
cathode
what device is pre-reading?
kVp meter
which device is electronic, w increments of 0.001 sec?
timer
what changes AC to DC?
rectifier
what is surrounded by a negatively charged focusing cup
filament
what is composed of solid-state, silicon-based diodes?
rectifier
what’s located in the XR circuit btw the high-voltage transformer & the XR tube?
rectifier
what measures tube current?
mA meter?
what spins @ 3300 or 10,000 rpm?
anode
what device uses max heat storage ability of the tube to deliver mAs?
falling load generator
source of bream’s & char. XR’s
anode
most commonly used AEC?
ionization chamber
what is turned by a rotor?
anode
activating the rotor
reduce tube life
when making an exposure, the tech should…
activate the rotor & exposure switch in one contin. motion
thermionic emission causes?
e-‘s to boil off filament
the e- stream passes from cathode to anode bc of ______ passing through the XR tube
current
heat is produced in XR tube as?
e-‘s interact w target material
most of the energy conversion in XR tube produces?
heat
XRs are produced as incident e-‘s interact w target atoms by a process called
bremsstrahlung
XRs are produced as incident e-‘s interact w inner shell e-‘s in target atoms by a process called
characteristic
percentage of energy in XR tube that is converted into XRs
1%
what can ionize matter/gas & affect film emulsion
XRs
the XR beam is ______/______ (consisting of many diff energies/wavelengths)
heterogenous/polyenergetic
XR emission spectrum consists of:
discrete (char. XRs) & contin. (brems XRs)
primary purpose of filtration
rad protection
total filtration is no less than
2.5 mm Al equivalent
what makes up inherent filtration?
glass envelope, tube housing, oil
what makes up added filtration?
Al
what produces pulsating DC w 120 pulses per sec & 100% ripple
single-phase, full-wave rectification
what produces DC w 13% ripple?
3-phase, 6-pulse
what produces DC w 4% ripple?
3-phase, 12-pulse
when changing from single-phase to 3-phase, 6-pulse the avg photon energy increase?
35%
when changing from single-phase to 3-phase, 12-pulse the avg photon energy increase?
41%
marks on focal track/spot of anode from bombardment of e-‘s
pitting
what states that electrostatic force is directly proportional to the product of the electrostatic charges and inversely proportional to the square of the distance btw them
Coulomb’s law
what states that energy of a photon is directly proportional to its frequency
Planck’s Quantum Theory
what can be created by friction, contact, or induction?
electrification
no resistance to e- flow below a critical temp (titanium, niobium)
superconductor
any substance through which e-‘s flow easily; variable resistance; obey Ohm’s law; requires V (copper, Al)
conductor
material that under some circumstances behave as insulator and in others a conductor; basis for computers (silicon, germanium)
semiconductor
does not allow e- flow; extremely high resistance (plastic, rubber, glass)
insulator
relationship btw electric resistance & electric current?
inversely
Ohm’s law
V=IR (I is current in amps)
unit of current
ampere (A)
unit of power
watts (W)
formula for power?
power (W) = V x current (A)
P=IV, or P=IIR
formula for total resistance in a series circuit
Rt = R1 + R2 + R3
formula for total resistance in a II circuit
1/Rt = 1/R1 + 1/R2 + 1/R3
lines of magnetic field are always
closed loops
ability of material to attract lines of magnetic field intensity
magnetic permeability
degree to which material can be magnetized
magnetic susceptibility
very slightly attracted to a magnet & ar loosely influenced by an external magnetic field; weakly attracted to both poles of a magnetic field
paramagnetic materials (MRI contrast)
weakly repelled by either magnetic pole; cannot be artificially magnetized; not attracted to magnet
diamagnetic materials (water, plastic)
strongly attracted by a magnet; usually can be permanently magnetized by exposure to a magnetic field
ferromagnetic materials (iron, nickel, cobalt, alnico)
lines of magnetic filed leave ____ pole and enter _____ pole
N to S
transform mechanical energy into electrical energy
electric generators
transform electrical energy into mechanical energy
electric motors
states that an electric current is induced in a circuit if some part of that circuit is in a changing magnetic field (no current is induced if the magnetic field is not moving)
Faraday’s Law
magnitude of induced current depends on what 4 factors
strength & speed of magnetic field, # of turns in the conductor & angle of conductor to magnetic field
energy dissipated by resistance in the wire used to wind a coil is called
copper loss
magnetic friction in the core due to changing magnetic field
hysteresis loss
power loss due to electric currents induced in the core
eddy current loss
how many types of transformer loss?
3 (copper, hysteresis, eddy current)
2nd law of electromagnetism thats states that the induced current flows in a direction such that it opposes the action that induces it
Lenz’s Law
if an atom loses an e-, it becomes a?
pos. ion
largest source of natural enviro rad?
radon
radon is produced by the natural decay of
Uranium
XR’s discovered on?
Nov. 8 1895
most common hip break is
femur neck
cecum located in
RLQ
