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electrostatics/ elec
| Question | Answer |
|---|---|
| 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
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