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electrostatics/ elec

QuestionAnswer
Electrostatics Study of e-s at rest
Force Push or pull
Ion The gain or lose of an electron by an atom (s)
matter be electrically charged by the movement of what? E-s
What is electrification? The gain or lose of an electron from matter
What are three causes of electrification? Friction, contact, and induction
What is friction Rubbing and confers same charge ex. tree static on film
What is contact Touching and confers same charge ex. Smudge or Cohen static on film
What is induction No physical contact between 2 objects and conveys an opposite charge
What is a Coulomb? Unit of electrical charge
1) laws of electrostatics Unlike charges attract; like charges repel
2) electrostatic force is directly proportional to what The product of the electrostatic charges and inversely proportional to the square of the distance between them (Coulomb)
3) when a object is electrified (gain or loss of an e- from matter) The e-are distributed evenly within or outside the object ex. Cooper wire
4) the charge is more concentrated along what? The sharpest curve of the surface
There is more concentration in a small area T or F? True
What method of arranging elements into related groups was invented by Dimitry mendeleye? The periodic table
Electrodynamics Studies charges in motion
What is current? The flow of e-s
Amp or amperage is the unit of measurement for? Current
What is thermiotic emission? The process of Boling off electrons at the filament
What is a circuit? A pathway that allows for the free flow of electrons as long as there is a potential difference
What is the difference between amps and milliamps? 1/1000ths of a sec
Fluoro tube uses? Milliamps (doesn't need much)
Coolidge tube uses? Amps
What is electric potential difference? Excess of e-s at one end and a deficiency at the other sets up an electrical potential difference
What is the unit of measurement for potential difference? Volts
Kv is 1000 times more than what? Voltage
KeV is the unit of measurement of a single what ? Electron
KeV Kiloelectronvolt
Kvp Kilovoltspeaks
What are the states of matter? Conductor, insulators, semi-conductors, super-conductors
What are the characteristics and type of matter is a conductor? Copper, aluminum, and silver are types of conductors. A characteristic is resistance to current flow w/potential difference
What are the characteristics and type of matter is insulators? Rubber and glass are types of insulators. A characteristic is it does not allow for current to flow due to a high resistance and the potential difference required would be extremely high
What are the characteristics and type of matter is a semi-conductor? Silicon and germanium are types of matter. A characteristic is that it allows for some flow of current. We use semi-conductors
What are some characteristics and type of matter is a super conductor? Niobium and titanium are types of matter. A characteristic is that there is no resistance, there is a free flow of current without potential difference. Ex. MRI, cold temps required
What are some sources of current? Battery-which converts chemical into electrical energy
Dynamo/generator Converts mechanical energy into electrical energy
Solar Sun light
Atomic/nuclear Atomic energy plant
Geothermal Underground
What are some Conditions of current flow? In a vacuum,in gas, in ionic solution and in a metallic conductor
What is resistance/resistors? Against the flow of current
Unit of measurement for resistance? Is the ohm
Opposition to current flow One ohm is the resistance of a standard volume of mercury
What are some factors of resistance? Types of material/length-indirect/diameter-indirect/temperature-direct
What happens to Copper wire if we shorten it and have a larger bore? You would have the least amount of resistance which is an indirect relationship
What does a capacitor do? Stores a charge
What is an ammeter? It measures the amount of current flow
What is a voltmeter? Measures volts or potential difference
What is a switch? It opens & close a circuit
What is a transformer? It increases or decreases potential difference
What is a rheostat? It controls Ma & allows for variable resistance
What is a diode? A solid state (x-ray tube)
What is a transistor? A switch that can amplify signals
What is a series circuit? A circuit where all elements are connected in line along the same conductor/ old houses, all lights went out at once
How are ammeters connected? Always in a series
What is the difference between high voltage and Low Voltage? High Voltage throws you Low Voltage holds you
What is a parallel circuit ? It contains elements that bridge conductors/ most houses today have circuit breakers
What does voltmeters measure and how are they connected? Voltmeters measure the volts and the potential difference. Voltmeters are always connected parallel
Ohms law V=IR V=voltage/ potential difference I= current flow R= resistance to current flow
Ohms law Voltage across the total circuit or any part of the circuit is equal to current times resistance
DC ELECTRONS flow in one direction only Required for xray tube, use solid state semiconductor rectifiers to achieve
AC Alternating current, elections alternate in different directions like a sine wave
Trough vs crest
Wavelength Measured in angstrom .1-.5
Frequency Number of wavelengths/ unit of Measurement is Hz hertz
Amplitude Is the height of a wave
power Measured in watts P=IV P=power I= amp/current flow V=volts/potential difference
Power loss (due to heat resistance) P=I(2)R
what is magnetism the fundamental property of some forms of matter. any charged particle (e-s) in motion creates a magnetic field which is perp to motion of e-
what is the history of magnetism? 10,000 yrs ago in magnesia, magnetite also known as lodestone which attracts iron and steel
what is the largest magnet? earth
where in radiology do we use magnetism? in MRI
in regards to magnetism/magnets how do the e-s rotate? e-s spin on their own axis clockwise and counter clockwise. you need an odd number of e-s. if even they cancel each other out. An odd # of e-s set up an sets up a magnetic force field
whats a magnetic dipole? equal ends but opposite charges
magnetic domian accumulation of dipoles
magnetic field lines of force which indicate direction for magnetic force
the closer you are to the magnet the? stronger the magnetic field
MRI uses coils that are placed around the pt. which give off what? R/F signals
the larger the magnet the .....? stronger the force outside of the magnet
the lines of force inside a magnet run which way ? run from S pole to N pole
the lines of force outside a magnet run which way? run from N pole to S pole
magnetic permeability the ability of a material to (absorb)attract lines of force or how susceptible matter is to become magnetized.
magnetic retentivity how long matter will hold magnetization
what is the indirect relationship of magnets? magnets are highly permeable but there is a low retention of magnetism w/matter
what are the three classifications of magnets? natural, artificial, and electromagnet
natural magnets earth and lodestone
artificial magnets bar magnet
electromagnet wire wrapped around iron core. ex. fire doors- when the alarm is pulled the circuit is opened.
electromagnet induction self and mutual one wire for self and two wires for mutual
what are the four stages of matter? non magnetic, ferromagnetic, paramagnetic, and diamagnetic
nonmagnetic matter material that is unaffected when in a magnetic field (wood, glass, plastic)
ferromagnetic matter strongly attracted by magnets (iron, colbalt, nickel)
paramagnetic matter slightly attracted by magnet (MRI contrast) gadolinium
diamagnetic matter weakly repelled by magnet (bismuth, and lead)
laws of magnetism 1) 1) every magnet has a north and south pole
laws of magnetism 2) 2) like poles repel; unlike poles attract
laws of magnetism 3) ferromagnetic material can be magnetized when in an external magnetic field.
laws of magnetism 4) 4) the intensity of filed is directly related to magnetic pole strength and indirectly related to distance squared
unit of measurement for magnetism? guass - old term, new term is telsa telsa= 10,000 G HHMC MRI- 1.5T/ RAPA-3.0T
what force is associated with electromagnetism with e- in motion Orsteads experiments/ compass
what is electromagnetic induction? it means to bring forth on or to get started
what are three ways to produce alternating current? 1. by moving the conductor across a stationary magnetic field 2. by cutting a stationary conductor with magnetic lines of force 3. by placing the stationary conductor with a varying magnetic flux
what is an armature (conductor)? a piece of copper wire that rotates on an axis
when a conductor is perp no current flows
when a current is parallel current flows
laws of EM induction/ Faradays law an electric current is induced to flow in a circuit is in a changing magnetic field
what factors control faradays law magnetic strength speed of magnetic field past conductor angle cuts conductor # of turns in conductor = more concentration like sharpest curve in copper
how many cycles per sec/ alternations? 60 cycles per sec 60 hz(frequency) 2 turns or alternations per/cycle
laws of EM induction/Lenzs law induced current flows in a direction that is opposite the action that induces it
EM devices/ what is a helix a coil of wire
EM devices/ what is a solenoid? a coil of wire connected to a source that carries current which sets up a magnetic field a solenoid can become a lock
EM devices/ what is an electromagnetic device? coil of wire carrying a current with an iron core in coil ( remote control devices, detent locks, fire doors)
what are the functions of a solenoid locks bucky, detents tube. if there is no current the locks dont work
what is EM self(auto) induction a coil of wire with a constant potential difference that gives you unimpeded current
how many coils does EM self induction use uses a single coil autotransformer
AC varying current through coil would make potentail difference and magnetic field vary
with first circuit closed an opposite voltage and current flow is set up
what is a (auto)transformer? any device that incr. and dec. voltage a single coil that induces current to flow
what side is the transformer on? the primary as to not receive a high voltage shock. allows you to select KVp
if 3 phase how many auto transformers are there? 3
how is the pre-reading kVp meter connected? in a parallel series
auto transformers work off of what EM self induction which is one coil of wire
voltage x amperage= power
EM mutual induction primary coil and secoundary coil
primary coil potential difference creates current flow. also sets up magnetic field that cuts through 2nd coil to induce opposing potential difference and induced current
secondary coil -caries induced current -nduced current creates a magnetic field around 2nd coil that cuts 1st coil to keep current flowing. - no moving parts or contact
electromagnetic field lines of force that cuase induced current to flow in the opposite direction
step up transformer works off EM Mutual induction increases voltage to kVp decreases amperage to milliamps more turns on secoundary coil higher tension transformer
step down (filament transformer) works off EM Mutual induction -decreases kVp back to voltage -6-10v increases Ma back to amperage -3-5amps/fluoro .5-5Ma more tunrs on primary coil used to produce filament current
what do we use in our system (only used for filament circuit) we use step down filament transformer (the primary coil carries more turns than the secoundary
where does the step down attach attached to the filament of the tube on secoundary side of high voltage transformer
what is a generator/dynamo? converts mechanical energy into electrical energy
what is a motor (fan)? it converts electrical energy into mechanical energy
what is a rotor? it has a motor which cuases (3,400-10,000rpm) the anode to spin
what are the types of transformers from simplest to most efficient? air core open core closed core shell type
what does transformers work off of? they all work off of mutual induction and they all have two coils
transformer inefficiency resistance, hysteresis, and eddy current
what is resistance? loss of power due to heat
what is hysteresis? due to a changing magnetic field
what is Eddy current? swirling current due to AC -use laminated cores
Created by: eckoultd1972