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Physics
Unit#2
| Question | Answer |
|---|---|
| Magnetic domain is also known as: | Magnetic dipoles |
| _________ ________ is the process of making ferromagnetic material magnetic: | Magnetic induction |
| _________ _________ is an accumulation of many atomic magnets with their dipoles aligned: | Magnetic domain |
| ___________ ________= domians point in different directions and cancel one another out: | Un-magnetized steel |
| _________ ________= domains are pulled about until they point in the same direction, thus reinforcing each other: | Magnetized steel |
| The more domains that are aligned the _______ the magnetic field in the material: | Stronger |
| ___________ _______ is a group of atoms with their magnetic field moving in the same direction: | Magnetic domain |
| Magnetic lines of force always flow from _______ to _______ outside the magnet: | North to South |
| Magnetic lines of force always flow from _______ to _______ inside the magnet: | South to North |
| __________ is the study of the relationship between electricity to magnetism: | Electromagnetism |
| Material or object that produces a magnetic field: | Magnet |
| Ability of a material or object to attract certain objects: | Magnetism |
| Ease in which a material will be magnetized: | Permeability |
| Ability of a material to stay magnetized: | Rententivity |
| __________ are highly attracted to a magnetic field, easily magnetized and have a high permeability: | Ferromagnets |
| _________ lie between highly attracted material and unaffected materials: | Paramagnets |
| Materials that are unaffected and repel magnetic fields: | Diamagnets |
| Examples of ferromagnets: | Iron, steel, cobalt, nickel and alloys: Alnico & permalloy |
| Examples of paramagnets: | Liquid oxygen, contrast agents used in MRI |
| Examples of diamagnets: | Water, wood, rubber, oil, glass, plastic, graphite and metals: mercury, bismuth, lead, gold |
| Naturally occurring magnets: | Earths magnetic field and lodestone |
| Force between two magnetic fields is proportional to the product of the magnitudes & inversely proportional to to the square of the distance between them: | Inverse square law |
| How does current flow along a conductor: | Flemings right hand rule |
| The fingers in Flemings law represent: | the direction in which magnetic field lines surround the conductor |
| The thumb in Flemings law represent: | The direction in which the current (electron) flow |
| A charge at rest produces ______ current: | None |
| A charge in motion produces a _________: | Magnetic field |
| A magnetic field at a constant produces _______ current: | No |
| Magnetic field in motion produces _______: | Current |
| The current runs _____ to ______ outside the solenoid: | Postive to Negative |
| The current runs ______ to ______ inside the solenoid: | Negative to Positive |
| __________ refers to a loop of wire wrapped around a metallic core that produces a magnetic field when an electric current passes through it: | Solenoid |
| Magnetic fields can be concentrated by _____: | Coiling the conductor |
| The magnetic field is strongest at which location: | Center of the coil |
| __________ are important because they can create controlled magnetic fields and can be used as electromagnets: | Solenoids |
| A _________ through a conductor will produce a magnetic field (force): | Moving electric charge |
| List 4 ways a field or force can be increased: | -Increased current -Wrapping a wire into a coil and passing current thru it -Increasing the # of coils -Inserting a conductor into the core of the coil |
| An EMF is also known as: | Voltage |
| The amount of induced current or strength of force depends on what 4 things: | -# of turns/coils in a conductor -Direction -Strength of the magnetic field -Speed of motion between magnetic lines of force & conductor |
| _____________ is the ability of an AC to switch directions: | Self-induction |
| _____________ allows DC to flow whild hindering AC: | Self-induction |
| _____________ is when electricity is produced when 2 coils are placed together and a varying current supplied to the first coil induces a similar flow in the second coil: | Mutual induction |
| The coil supplied with the current is called the ________ coil: | Primary |
| The coil in which the current is induced is called the _________ coil: | Secondary |
| __________ ________ is the concept that the current through one inductor can induce a voltage in another nearby inductor: | Mutual inductance |
| An autotransformer is an example of _______ induction: | Self |
| An electric generator is used to: | Convert kinetic energy to electrical energy |
| An electric generator works by: | Electromagntic induction |
| The addition of a commutator ring does what: | Generates DC |
| A commutator ring changes the ________ of the contact on the loop of wire causing ______: | Polarity, current to reverse |
| An electric motor does what: | Converts electrical energy into mechanical energy |
| 3 phase converts to ____: | DC |
| ___________ _______ is a kind of motor that converts electrical power to mechanical power in its rotating part: | Induction motor |
| The stator is located on which side of the xray tube: | Primary |
| The stator is _________: | Stationary |
| The rotor is located on the _______ side of the xray tube: | Secondary |
| List 3 important transformers in the xray circuit: | -High voltage transformer -Filament step-down transformer -Autotransformer |
| _______________ transformer raises the incoming-line voltage to the kilovoltage range necessary for xray production: | High voltage step-up |
| ___________ transformer decreases the incoming line voltage to the voltage and ampere range used to heat the filament: | Filament step-down |
| ___________ varies the incoming voltage to an appropriate level for the high voltage step up transformer: | Autotransformer |
| A transformer with more turns in the secondary coil increases voltage and ________ current, proportional to the turns ratio: | Decreases |
| A step-down transformer __________ voltage and _________ current: | decreases, increases |
| List the three functions of an autotransformer: | -Provides voltage for xray filament circuit -Provides voltage for primary of the high voltage transformer -Provides a location for kvp meter that indicates voltage to be applied across the xray tube |
| Autotransformer consists of a _________ winding wound on a closed core and works on _______ _______: | Single, self induction |
| If the turns ratio is greater than 1 the transformer is a __________: | Step -up |
| If the turns ratio is less than 1 the transformer is a ________: | Step-down |
| Formula for turns ratio: | # of turns in secondary coil/# of turns in the primary coil |
| Voltage & current have a _________ relationship: | Inverse |
| __________ _______ control the current to the primary coil of the transformer: | Exposure timers |
| List the 3 types of Exposure timers: | -Modern electronic timer -mAs timers -AEC |
| Of the 3 types of exposure timers, which can be controlled by the technologist: | -mAs timers -Modern electronic timer |
| Which type of exposure timer cannot be controlled by the technologist: | AEC |
| AEC controls _________: | Time only |
| What is the most commonly used type of exposure timer used today: | Modern electronic timer |
| _________ is the most sophisticated, complicated and accurate type of exposure timer: | Modern electronic timer |
| _________ allows for the widest range of time intervals and is accurate to intervals as small as 1ms: | Modern electronic timers |
| ______________ type of exposure timer measures the quantity of radiation reaching the IR and automatically terminates exposure when sufficient radiation has been received: | AEC |
| This type of exposure timer can be manipulated but not controlled: | AEC |
| _________ type of exposure timer provides the highest safe tube current for the shortest time of exposure for any mAs selected: | mAs timers |
| All ____ controls allow adjustment of amount of radiation necessary to send the exposure termination signal: | AEC |
| Reason electronic timers are used: | Shortest exposure time possible to prevent overexposure and unnecessary patient exposure |
| Back-up time is used to: | eliminate overexposure to patient and overloading the tube |
| When AEC is activated the ______ ________ ________ ________ becomes the back up timer: | Main exposure time control |
| The maximum exposure time can not exceed: | 800 mAs |
| Which regulatory agency regulates the maximum exposure amount: | Dept of Health, Education and Welfare |
| A computerized control system that is like a preprogrammed technique chart: | APR |
| Subdivisions of the control concole: | mA, time, FSS, line voltage compensator, AEC |
| The step up transformer controls: | Rotor/target & filament |
| The step down transformer is not connected to which two parts of the tube: | Rectifiers & filament |
| kVp is not converted from volts to kilovolts until after which item: | Step-up transformer |
| ________ allows electric current to flow in one direction, but blocks it in the opposite direction: | Diodes |
| Rectifiers are used to _______: | Convert AC to DC |
| A transformer is used to ________: | Increase or decrease voltage in AC only |
| The frequency in AC current from a wall plug is ____ cycles per second: | 60 |
| The duration of a complete cycle is ______ of a second for a full sinusoidal wave: | 1/60th of a second |
| AC from a wall plug changes direction ______ times per second: | 60 |
| All components of the control console and high voltage section operate with what type of current: | AC |
| Xray production cannot occur using which type of current: | AC |
| What component is necessary to change AC to DC so the cathode will not burnout due to overheating by a reversed current: | Rectification |
| List the two types of rectifiers: | Vacuum valve tube & solid state |
| What was the first material used in vacuum valve rectifiers: | Selenium |
| The electrons in a rectifier flow in only one direction, is it (+) to (-) or (-) to (+): | (-) to (+), cathode to anode |
| Which type of rectifiers are in all tubes used today: | Solid state |
| Solid state rectifiers use what material: | Silicon with semi conductors |
| List the 4 advantages of a solid state rectifier: | -smaller -lower resistance, lower voltage drop & less reverse current -no filament burnout (no filament) -less heat=longer lifetime |
| The cathode side of a solid state rectifier is made from a n-type semiconductor, also known as a _______: | donor |
| The anode side of a solid state rectifier is made of a p-type semiconductor, also known as a _________: | Acceptor |
| ___-type of semiconductor has a surplus of loosely bound and freely movable electrons: | N-type |
| ___-type of semiconductor has spaces called holes that are very mobile where there are no electrons: | P-type |
| When a tube has no diode it is known as ___________: | self rectification |
| _____________ forces the tube to act as the diode causing burn-out | Self rectification |
| When -type and n-type semiconductors are joined it is called: | P-N junction |
| Current will only flow if the ______ side of the battery is connected to the _______ side of the rectifier: | Negative to Negative, it repels the current and current flows |
| When current flows it is known as, ________ _____: | Forward bias |
| When current is blocked and there is no flow through the rectifier it is called, ________ ____: | Reverse bias |
| Disadvantages of self rectifiers: | uses only upper positive half of sinusoidal wave to produce xrays, exposure time is 2x as long -repeated or prolonged exposure causing tube failure by overheating |
| Self rectifiers give _____-wave rectification and output occurs only ____ times per second: | Half-wave, 60 |
| List the three types of rectifiers: | Self-rectifiers, half-wave rectifiers, full-wave rectifiers |
| With half wave rectifiers the diode is placed in _______ to protect the tube: | Series |
| In half wave rectifiers the _______ side of the AC wave is passed easily, while the other half is blocked: | either |
| In half wave only ______ of the electrical wave is used to produce xrays: | half, either positive or negative side of the sinusoidal wave |
| Half-wave rectification gives only _____ pulses per second: | 60 |
| With full wave rectifiers, ______ side(s) are used to produce xrays: | Both |
| Most effieicient rectifier: | Full wave |
| ______-wave rectifiers convert both polarities of the AC waveform to DC: | Full |
| When four diodes are placed in a series to form a brifge it is known as, _________ _______: | diode bridge |
| ________ is an unwanted phenomenon in the xray production due to the lengthening of the exposure time and the reduction in the average kV: | Ripple |
| Decreased ripple ______ efficiency: | Increases |
| One diode produces _______ rectification: | Half-wave |
| List the two types of power in the xray tube: | Single or three-phase |
| Single phase generators with full wave rectification produce a voltage ripple of ___ pulses per Hz or pulses per second, which produces a ____% ripple: | 2, 100% |
| Genrator power that allows potential difference to drop to zero with every change in the direction of current flow: | Single phase |
| An alternating swing in voltage from zero to maximum potential of 120 times each second, results in a ________ xray beam: | Pulsating |
| _______ phase generators produce an almost constant potential difference across the xray tube: | Three pahse |
| _______ phase generators never drop to zero: | Three-phase |
| List three advantages of three phase generators: | -Greater efficiency of xray production -More constant potential -Lower operating cost |
| List the three different types of three phase generators: | -Three-phase six-pulse -Three phase 12 pulse -High frequency |
| The best three phase generator is _______ ________: | High frequency |
| _______ _______ generators use AC and DC power convertors to change the incoming line voltage frequency from 60 Hz to the 5,000 Hz range: | High frequency |
| High frequency generators produce in the range of ______% generator ripple: | less than 1 |
| Three phase 12 pulse produce ___% of ripple: | 4-10 |
| Three phase six pulse generators produce ___% of ripple: | 13-25 |
| List five advantages of a high frequency generator: | -Smaller-cost less to operate -Nearly constant potential voltage waveform -Better image quality -Lower patient dose |
| Three pulse produce a voltage ripple of ___ pulses per Hz or ____ pulses per second: | 6, 360 |
| Three phase 12 pulse produces 12 pulses per _____ second or ____ pulses per second: | 1/60th, 720 |
Created by:
akhernandez19