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X-ray Circuit Stack
Components of the Xray circuit
| Question | Answer |
|---|---|
| Device used to test the exposure timer of a single phase unit | spin-top |
| The autotransformer is in this circuit | primary |
| What device provides means of neutralizing a charged body | ground |
| What two devices protect circuit unit | ground and circuit breakers |
| What is the resistance of a standard volume of mercury under standard conditions called | OHM |
| What is the amount of electric charges flowing per sec through a conductor called | current |
| The electrical potential is the product of current and resistance is what law | OHMS law |
| The difference in electrical potential between two points is measured in | volts |
| What is the device called that impedes or slows electricity | resistor |
| What is the unit of measure for current | ampere |
| What type of current does a battery produce | direct current |
| What is the pathway of an electric current called | electric circuit |
| What is the unit of measure for resistance | ohm |
| What device protects the circuit from overload | circuit breaker |
| If resistance decreases, current in an electric circuit ________ | increases |
| Which component in the x-ray circuit requires a step-down transformer | filament circuit |
| What is the principle purpose of the autotransformer | adjust voltage |
| What does the pre-reading volt meter do | predicts voltage in the secondary circuit |
| An electromagnetic device that changes alternating current from low to high is | step-up transformer |
| What device operates on self-induction | autotransformer |
| The ________ circuit provides electrons to be pushed across the x-ray tube | filament |
| The electricity of the filament circuit must be ________voltage, ________amperage | low voltage, HIGH amperage |
| What type of timer is most accurate, by 1ms | electronic timer |
| The mAs timer is usually set to give the _______mA at the shortest time | highest |
| What is the purpose of the back up timer | limit unnecessary x-ray exposure |
| The AEC unit is ultimately controlled by | patient thickness |
| The AEC measures | radiation that is transmitted through the patient |
| If the AEC is activated for the table buckey but your doing table top what will happen | an inappropriately long exposure will occur |
| What is the spinning top test used to determine the accuracy of | exposure time |
| What part of the circuit is grounded | secondary of the step-up transformer |
| What are some components of the secondary circuit | x-ray tube, rectifiers, secondary coil of step up transformer, milliammeter |
| When does the milliammeter register in a radiographic unit | during the activation of the exposure stage of the exposure switch |
| Where is the milliammeter located | connected to the mid-point of the secondary coil of the transformer |
| What two circuit devices conduct current in one direction | valve tubes, solid state diodes |
| The rectifier works by allowing current to flow through it in which direction | one direction only |
| Why is rectification used in x-ray equipment | to produce direct current |
| What is the transformer law and its variation | emf or potential difference, turns and amps have a direct relation, but current has an inverse relation |
| What are the two types of electromagnetic induction | self-induction, mutual-induction |
| When does self induction take place | only occur while magnetic flux is changing direction |
| What is the difference between mutual and self induction | mutual induction involves a transformer with two coils the alternating current in primary induces the secondary coil, self induction the coils are intertwined as one so direction of emf is opposite applied KV |
| When is an alternating current present | when e’ constantly change direction |
| What is the conventional electrical flow and the electrical flow needed in the tube | normally, positive to negative, tube flow is negative to positive or it will damage tube |
| How is a current produced | excessive pressure or voltage on one side pushes e’through |
| What is the maximum difference of potential between two terminals of a battery or generator | EMF |
| What is the property of the circuit that opposes or hinders the flow of electric current because something is in use | resistance |
| On a circuit, if the switch is closed is there flow or is flow off | FLOW, opens stops flow |
| What is ground potential | always zero, that’s why it neutralizes so well |
| What circuit boosts Voltage to necessary x-ray range and permits radiographer to adjust kV and mAs | Primary circuit |
| What circuit contains, main switch, exposure switch, transformers, timer circuit, filament circuit | Primary circuit |
| What side of the unit has high voltage, rectification circuit and rotor stator | secondary side |
| The step-up transformer separates the unit into what | low and high voltage |
| What two transformers operate on mutual induction | step-up and step-down transformers |
| What is mA measured in and what dictates mA | measured in amps, filament circuit dictates mA |
| When is the current in the circuit direct instead of alternating | when it gets to the rectifier |
| What does the battery provide in the circuit | provides electric potential, voltmeter measures electrical potential |
| What does the capacitor do | momentarily stores electric potential |
| What is the rheostat | variable resistor |
| What do AECs measure | preset quantity of radiation |
| what are phototimers and ionization chambers | types of AECs |
| What are the properties of the x-ray circuit | potential difference, current, resistance |
| When a circuit breaker, breaks what really happens | breaker opens circuit stopping current flow |
| What is the principle for transformer operation | electromagnetic induction |
| Self-induction at the autotransformer allows a radiographer to set | kV |
| What is the difference between the pre reading volt meter and volt meter | volt meter measures volts on primary side, pre reading volt meter predicts what is on secondary side |
| List some timers | electronic, mA, AEC, mechanical, back up timer |
| What are some most common timers used | electronic timers, mAs timers |
| What kind of timer is a AEC timer | controlled timer |
| What is the back-up timer set by and its purpose | the radiographer, determines what longest exposure could be |
| The rectifiers are located between the secondary of the step-up transformer and the x-ray tube T or F | TRUE |
| What part of the circuit is grounded for safety measure | secondary coil of the step-up transformer |
| What one transformer operates on self-induction | autotransformer |
| T or F a battery is a source of Direct current | TRUE |
| What is potential difference measured in | volts |
| Does the line voltage compensator compensate for incoming line voltage fluctuations | yes |
| How many dots will be demonstrated from a single phase full wave x-ray unit for 1/12sec. | 5 dots ( 60x1/12) |
| The effective voltage with three phase 12-pulse is _______% of the kVp selected | 96 |
| What is the main advantage of three phase over single phase current | voltage never drops to zero |
| Full wave rectification produces what kind of current alternating or direct | direct |
| What part of the circuit are the rectifiers located in | secondary, high voltage side |
| What is the current between the secondary of the high tension transformer and the rectifiers | alternating current |
| What is the voltage ripple with a single full wave rectified unit ____% | 100% |
| What is the Voltage required to move four amperes against the resistance of 10 ohms | 40V |
| The step down transformer will have a turns ratio of greater or lesser than one | lesser than one |
| What are devices that make the negative half of the cycle useful | rectifiers |
| Type of electricity in the primary circuit | alternating |
| What is the unit of measure for electromotive force | volt |
| What is the general location of the filament | cathode |
| The milliammeter is in this circuit | secondary |
| Direct current is provided by | a battery, rectifier circuits |
| What device in the circuit is also known as the mA selector | rheostat |
| What is another term to indicate the force causing electrons to move in a circuit | potential difference |
| What device converts volts to kilovolts | step-up transformer |
| What device adjusts voltage | autotransformer |
| What is the unit of measure for resistance | OHM |
| The circuit characteristic that opposes electron flow | resistance |
| What device produces x-rays | x-ray tube |
| What part of the circuit is the autotransformer in | primary or low voltage side |
| What is the source of free electrons | filament |
| What does the filament circuit control | number of electrons passing from cathode to anode, amperage to voltage |
| The more thermionic emission the more _______produced | x-rays |
| What does the filament circuit operate on | 3 to 5 amps and 6-12 voltage and uses step-down transformer |
| Is the ammeter connected in series or parallel | series |
| When does the ammeter measure mA | during the exposure only |
| What are the classifications of conductors | non-conductor and semi-conductors |
| What is a non-conductor and an example | resist movement, poor conductivity, wood or glass |
| What is a semi-conductor and an example | sometimes conduct and sometimes insulate depends on conditions, silicon |
| What are conductors | conductivity –will allow electrons to flow like copper |
| What are the forms of rectification | single rectifier diode, two rectifier diode and four rectifier diode |
| What does the single rectifier diode do | suppresses negative half of the cycle |
| What does the two rectifier diode do | suppresses negative half of cycle and the other diode increases efficiency |
| What type of rectifier diode is most used | four rectifier diode |
| What does the four rectifier diode do | doesn’t suppress negative half of the cycle, it redirects ti through the tube to cathode to anode flow |
| What is the minimum reaction time | determine length of time for the AEC to respond to radiation for generator to stop it |
| What dictates length of exposure on AEC | patient thickness dictates length of exposure |
| What is the minimum response time range from manufacturers that x-ray unit is capable of | .05 - .005 sec. |
| What is expected from a radiographer if using AEC | positioning to be accurate |
| Does the radiographer select response or exposure time | exposure, response is selected by AEC |
| Automatic exposure equipment permit what to be set to protect patient and unit from over exposure | back-up time- absolute time AEC will shut off |
| What are some rules for the back-up timer | cannot exceed tube limit, should be set 150% of anticipated mAs |
| Mechanical timers can be off by | .25sec |
| How do you check timer on full wave rectification | 3-phase wave forms put together for 120 degree sequences |
| How many impulses do full wave rectification have_____ | 120 |
| What does a rectifier do | redirects negative side of wave so the flow is from cathode to anode in DC |
| What are the properties of an electric current | potential difference (emf or voltage), current (measured in amps) and resistance (measured in ohms) |
| What is potential difference | a diff in electrical potential energy between two points in an electric current |
| What is emf | applies to the max diff of potential between 2 terminal s of a battery or generator |
| What is volt | the unit of potential difference defined as that potential diff which will maintain a current of one ampere in a circuit whose resistance is 1 ohm |
| What is current | the amount (quantity) of electric charge flowing per second in amps |
| What is an ampere | 1 coulomb quantity of electric charge flowing per sec (6.25x10^18 free e’ per sec |
| What is resistance | opposes or hinders flow in the circuit measured in ohms |
| What is ohms law | I=V/R where I is current, V is potential diff and R is resistance |
| Can ohms law be applied to the whole circuit or just a portion of the circuit | both |
| What does a circuit have to have | a conductor, load, and a switch to turn on/off |
| How does DC flow | one way always, from negative to positive |
| What does an ammeter do | measures potential difference, attached in series |
| What does a voltmeter do | measures potential diff in 2 points, attached in parallel |
| What is the formula to find mAs, time and mA | mAs=T x mA |
| How do you ground a + charged body | e’ move up from the ground to neutralize body |
| How do you ground a – charged body | drives the excess e’ to the ground to neutralize |
| What does the circuit breaker do to protect against overloading | opens to stop flow when overload is sensed |
| What does a transformer do | changes AC form high to low (step down) or low to high (step up) |
| What always surrounds a conductor in which an electrical current is flowing | a magnetic field |
| Can a magnetic field induce an electrical current | yes by a conductor moving through a magnetic field, or a magnetic field moving across a conductor |
| When does self induction occur | while the magnetic flux is changing |
| What does self induction allow | kV variation |
| What is essential in mutual induction | to have 2 coils |
| What is the transformer law | Vs/Vp=Ns/Np (direct relation) |
| What is the variation of transformer law | Is/Ip=Vp/Vs (inverse relation) |
| What is the autotransformer law | Vs/Vp=Nstapped/Np ( Vs=VpxNs tapped/Np ) |
| What is tapped | selects how many coils will be selected when selecting kV at the autotransformer |
| What does the autotransformer determine | what voltage is applied to the primary side of the step up transformer |
| What does the autotransformer function on | electromagnet but self induction |
| What is the pre-reading voltmeter connected in | parallel |
| How does AEC work | senses how much radiation passes through the patient and when predetermined amount passes through, it will turn off automatically |
| Exposure will be _____ if patient is big compared to small with AEC | longer |
| Single phase self rectified uses what | 1 or 2 diodes, no valve tubes, and does this by itself with 60 impulses per sec (no negative half) |
| Single phase full wave rectification uses what | 4 rectifier diode (valve tube) with 120 pulses per sec (negative half foes from cathode to anode) |
| Will you see dots when using a spin top w/ 3 phase | no you will see an angle |
| In the filament, the _____ the mA, the _____ the heat will =____ e’ boiled off | higher, higher, more |
| What transformer does the filament circuit use | step down transformer |
| Is there an ammeter in the filament circuit | yes, it measures mA during an exposure |
| What does the secondary coil of the transformer do | gets us from voltage to kilovoltage |
| What is a milliammeter | measures miliamperage on the secondary circuit and is connected in series and grounded (works on low amperage) |
| What are the 2 types of rectifiers | vacuum diode tube and solid state diode |
| What is the vacuum tube diode | aka valve tube, is an evacuated glass tube w/ 2 electrodes (cathode- and anode+) where current will flow from – to + (cathode to anode) |
| What is a solid state diode | device that uses semiconductors to conduct current in one direction only |
| What does a 3 phase circuit use | 3 autotransformers, primary and secondary coils will have 3 turns and will sequence off of each other at 120 degrees |
| 3 phase 6 pulse = | 14% ripple; 86% kVp increase |
| 3 phase 12 pulse = | 4% ripple; 96% kVp increase; uses lower mass |
| Single phase half wave and single phase full wave = | 100% ripple |
| High frequency units use | power converters to convert incoming voltage frequency from 60 Hz to 6,000 Hz using very low mA |
| When is peak voltage achieved using high frequency units | 10% of the time necessary for 3 phase with less than 1% voltage ripple |
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