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Physic 2 Unit 1 HW
| Question | Answer |
|---|---|
| Which of the following principles of rectification produces the maximum efficiencyof x-ray production? | High frequency |
| To generate three-phase, six pulse power, at least how many rectifiers are necessary? | 6 |
| A semiconductor rectifier: | Is a solid-state device |
| If a single rectifier is inserted into a circuit that conducts 60 Hz AC so that is suppresses the positive portion of the waveform, then the output waveform will comtain: | 60 negative pulses per second |
| The voltage ripple associated with various x-rays generators is | 100% for self-rectification |
| A rectifier Converts | Converts AC to DC |
| In a circuit that contains a single rectifier: | Electron flows in one direction but not in the other |
| If 60Hz AC power if full-wave rectified, output voltage consists | 120 pulses per second |
| The current from a common household wall receptacle in the United States is | 60HZ AC |
| Thermionic emission refers to | Electron emission from a heated source |
| Which of the following is a symbol for a diode | ------>1-------- |
| The main advantage of full wave rectification over the half-wave rectification is | A greater number of x-rays per cycle |
| How many overlapping pulses are generated in 1s for threes-phase , six pulse power? | 360 |
| Full wave length rectified | 100% |
| High frequency | 1% |
| Three phase, six pulse | 13% |
| Three phase, twelve pulse | 4% |
| Self-rectified | 100% |
| Power to the primary side of the high-voltage transformer comes from the | Secondary side of the autotransformer |
| The output voltage from the autotransformer | proportional to the turns ratio |
| The autotransformer converts | Electric energy to electric energy |
| The autotransformer operates on the principle of | Faradays law |
| The principle purpose of the high voltage transformer is to do which of the following? | Increase voltage |
| The voltage supplied to an x-ray imaging system is 220V. The voltage used by the x-ray tube is produced by which of the following? | High-voltage transformer |
| The autotransformer has only one | Coil |
| The principle purpose of the autotransformer is to | Adjust voltage |
| Which of the following is directly connected to the autotransformer? | kVp meter |
| Taps on the windings of an autotranformer are used to select which of the following? | line compensation |
| The autotransformer can be used to do which of the following? | Increase kVp |
| In the design of an autotransformer | A single coil serves as both the primary and the secondary coil |
| Selection of kVp | Requires that constate voltage be supplied to the autotransformer |
| Line compensation | is required to stabilize voltage |
| Which of the following is uded to determine the voltage before exposure? | An autotransformer |
| The filament transformer | Increases current |
| The filament transformer is usually | A step-down transformer |
| The filament circuit | Begins at the autotransformer and ends at the filament |
| The unit mAs | could be expressed in coulombs |
| An exposure technique of 100 mAs at 100 ms compared with 50 mA at 50 ms results in | Four times the number of electrons |
| The control of the focal spot size depends on | The filament that is energized |
| The meter that monitors x-ray tube current is | physically located on the control console |
| x-ray tube current is usually measured in which of the following | milliamperes (mA) |
| The filament transformer is designed | with a turn ratio less than 1 |
| Which of the following would be correct to use for expressing x-ray tube current? | coulombs/second |
| The design of fixed mA stations requires the use of which of the following | precision resistors |
| mA is a unit of electric current, and mAs is a unit of | Electric charge |
| A radiographic technique calls for a 50ms exposure, but the exposure control has only fractional notation. Which of the following should be selected? | 1/20 s |
| A radiographic technique calls for a 400 mA, 1/20 s exposure. What is the mAs? | 20 mAs |
| If an x-ray imaging system is operated at 600mA, 50ms, the total mAs will be which of the following? | 30mAs |
| A radiographic technique of 100mA at 1/4 s has been used. If one changes to 500mA station, the appropriate exposure time for the same mAs is which of the following? | 1/20s |
| operation at 300mA for 1/20 s is equivalent to operation at 900 mA for | 17ms |
| The control of exposure time always | on the primary side of the high-voltage transformers |
| The exposure timer on a three phase radiographic imaging system will | be electric |
| An automatic exposure control(AEC)device: | can use an ionization chamber between the patient and the image recpyor |
| With an automatic exposure control (AEC) devic: | A back up timer is required |
| The shortest exposure possible eith single phase equipment is 1/120 s. How many milliseconds is that? | 8 ms |
| Mammography sometimes requires exposures as long as 1.5s.This is equivalent to which of the following? | 1500 ms |
| The shortest exposure possible with a three phase equipment is 1ms. What fraction of a second is that? | 1/1000 |
| There are 30 video frames each seconds for a fluoroscopic CRT dynamic image. What is the length for each frame? | 33ms |
| The human eye cannot visualize faster than approximately five veiws each second. what is the intergration time of the human eye? | 200ms |
| A radiographic technique calls for 86kVp/200mAs using the 800 mA station. What is the exposure time? | 250ms |
| Which of the following is contained in a typical high voltage generator? | diode rectifier |
| A change in the voltage waveform from the primary side to the secodary side of the high voltage transformer produces | Amplitude |
| In half-wave rectification, each inverse half-cycle in the primary circuit corresponds to how many voltage pulses across the x-ray tube? | None |
| Which of the following is higher for a single-phase high voltage generator than for a three-phase high voltage generator? | Voltage ripple |
| Which of the following is a disadvantage of three phase power compared with single-phase power? | High capital cost |
| The disadvantage of a self-rectified cicuit is | its limited exposure time |
| An exposure of 1/10 s | Produces twice as much radiation if full-wave rectified than if half wave rectified |
| Full wave rectification | requires at least four rectifiers |
| A rectifier | can be a semiconductor |
| Concerning the transformer used in the x-ray circuit | The high voltage transformer is a step up device |
| Which of the following is an advantage of three phase power over single phase power | increased x-ray intensity per mAs |
| Oil is used in the high voltage section of an x-ray imaging system for which of the following functions | Electrical insulation |
| Which power supply should provide the highest quality x-ray beam? | high frequency |
| Full wave rectified power | 100% |
| half wave rectified power | 100% |
| high frequency power | 1% |
| Three phase six pulse power | 13% |
| Three phase 12 pulse power | 4% |
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