X-ray Circuit Chapter 5 Exposures (Worksheets)

What is the approximate voltage ripple for, three-phase, 12-pulse?

4%

If a single rectifier is inserted into a circuit that conducts 60 Hz AC so that it suppresses the positive portion of the waveform, then the output waveform will contain: A. 60 negative pulses per second B. 60 positive pulses per second C. 120 negative pulses per second D. 120 positive pulses per second E. Variable pulses, depending on the frequency

A. 60 negative pulses per second

The shortest exposure possible with single-phase equipment is 1/120 s. How many milliseconds is that? A. 8 ms B. 17 ms C. 35 ms D. 50 ms E. 120 ms

A. 8 ms

In the design of an autotransformer: A. A single coil serves as both the primary and the secondary coils. B. The exposure timer is on the primary side. C. The major kVp adjustment and the line-voltage compensator are on the secondary side. D. The major kVp adjustment is on the primary side and the minor kVp adjustment is on the secondary side. E. There are separate primary and secondary coils.

A. A single coil serves as both the primary and the secondary coils.

The principle purpose of the autotransformer is to: A. Adjust voltage B. Increase voltage C. Rectify voltage D. Reduce voltage E. Stabilize voltage

A. Adjust voltage

A change in the voltage waveform from the primary side to the secondary side of the high-voltage transformer produces a change in: A. Amplitude B. Frequency C. Phase D. Velocity E Wavelength

A. Amplitude

A rectifier: A. Can be a semiconductor B. Converts DC to AC C. Increases current D. Increases voltage E. Increases x-ray intensity

A. Can be a semiconductor

The autotransformer has only one: A. Coil B. Meter C. Rectifier D. Switch E. Turns ratio

A. Coil

A rectifier: A. Converts AC to DC B. Converts DC to AC C. Increases voltage D. Refers to a type of electromagnetic device E. Refers to a type of electromechanical device

A. Converts AC to DC

The unit mAs: A. Could be expressed in coulombs B. Could be expressed in coulombs/second C. Is a unit of electric current D. Is a unit of electromotive force (EMF) E. Is electron/s

A. Could be expressed in coulombs

Which of the following is contained in a typical high-voltage generator? A. Diode rectifiers B. Autotransformer C. Exposure switch D. kVp meter E. mA meter

A. Diode rectifiers

mA is a unit of electric current, and mAs is a unit of: A. Electric charge B. Electric potential C. Reciprocal kVp D. X-ray beam quality E. X-ray beam quantity

A. Electric charge

Oil is used in the high-voltage section of an x-ray imaging system for which of the following functions? A. Electrical insulation B. Reduction of rotor function C. Reduction of voltage ripple D. Thermal conduction E. Voltage rectification

A. Electrical insulation

Thermionic emission refers to: A. Electron emission from a heated source B. Heat conduction C. Heat emission from an electric conductor D. Heat radiation E. Ionization with heat

A. Electron emission from a heated source

Which of the following is a disadvantage of three-phase power compared with single-phase power? A. Higher capital cost B. Higher electrical operating costs C. Limited kVp D. Longer minimum exposure time E. Softer radiation

A. Higher capital cost

In half-way rectification, each inverse half cycle in the primary circuit corresponds to how many voltage pulses across the x-ray tube? A. None B. One C. Two D. Four E. Twelve

A. None

The control of focal spot size depends on: A. The filament that us energized B. The mA station selected C. The secondary taps of the autotransformer D. The target angle selected E. The turns ratio of the filament tranformer

A. The filament that us energized

If V stands for voltage and T for the number of turns enclosed between the taps of an autotransformer, then the autotransformer law is which of the following? A. Vp/Vs=Tp/Ts B. Vp/Tp=Vs X Ts C. Vp/Vs=Tp X Ts D. Vs/Vp=Tp/Ts E. Vs=Vp

A. Vp/Vs=Tp/Ts

The voltage ripple associated with various x-ray generators is: A. 70.7% for single-phase, full-wave rectification B. 100% for self-rectification C. Higher for self-rectification than for half-wave rectification D. Highest with high frequency E. Less for single-phase than three-phase power

B. 100% for self-rectification

Peration at 300 mA for 1/20 s is equivalent to operation at 900 mA for: A. 8 ms B. 17 ms C. 60 ms D. 200 ms E. 500 ms

B. 17 ms

A posterior-anterior (PA) chest requires a technique of 125 kVp at 4 mAs. The total number of electrons used to make the exposure is: A. 2.5X10^15 B. 2.5X10^16 C. 2.5X10^17 D. 6.3X10^16 E. 6.3X10^17

B. 2.5X10^16

440V is supplied to 1000 primary turns of an autotransformer. If the desired output voltage is 100V, how many secondary turns must be tapped? A. 100 B. 227 C. 454 D. 4,400 E. 10,000

B. 227

If an x-ray imaging system is operated at 600 mA, 50 ms, the total mAs will be which of the following? A. 6 mAs B. 30 mAs C. 60 mAs D. 300 mAs E. 600 mAs

B. 30 mAs

220V is supplied to 800 primary turns of an autotransformer. What will the output voltage across 200 secondary turns? A. 27.5 V B. 55 V C. 880 V D. 1760 V E. 3520 V

B. 55 V

To generate three-phase, six-pulse power, at least how many rectifiers are necessary? A. 4 B. 6 C. 8 D. 12 E. 16

B. 6

A semiconductor diode: A. Allows current to flow only from n type of material to p type B. Allows current to flow only from p type material to n type C. Contains carries that are also called proton traps D. Contains holes that are also called proton traps E. It also called an electromechanical rectifier

B. Allows current to flow only from p type material to n type

The exposure timer on a three-phase radiographic imaging system will: A. Be automatic B. Be electronic C. Be synchronous D. Limit exposure to 1/60 s or larger E. Limit exposure to 8 ms and no shorter

B. Be electronic

The filament circuit: A. Begins at the filament and ends at the filament transformer B. Begins at the autotransformer and ends at the filament C. Controls kVp D. Is located entirely in the operating console E. Is located in all three of the major components of an x-ray imaging system: the console, the high-voltage generator, and the x-ray tube

B. Begins at the autotransformer and ends at the filament

An automatic exposure control (AEC) device: A. Can use a photomultiplier tube on the entrance side of the patient B. Can use an ionization chamber between the patient and the image receptor C. Cannot control exposures shorter than 1/120 s D. Does not require a manual timer E. Works only with three-phase and high-frequency power

B. Can use an ionization chamber between the patient and the image receptor

Which of the following would be correct to use for expressing x-ray tube current? A. Coulombs B. Coulombs/second C. Electron volts D. Kilovolt peak E. Kilovolts/second

B. Coulombs/second

In a circuit that contains a single rectifier: A. Electron flow is pulsed but uninterrupted B. Electrons flow in one direction but not the other C. the result is constant potential DC D. Twice as many electrons flow in the output coil as in the input coil E. Voltage is increased

B. Electrons flow in one direction but not the other

The principle purpose of the high-voltage transformer is to do which of the following? A. Adjust voltage B. Increase voltage C. Rectify voltage D. Reduce voltage E. Stabilize voltage

B. Increase voltage

The filament transformer: A. Has four windings B. Increases current C. Increases voltage D. Is an autotransformer E. Must have precision resistors

B. Increases current

Which of the following is directly connected to the autotransformer? A. Filament B. kVp meter C. mA meter D. Rectifier E. X-ray tube

B. kVp meter

A radiographic technique of 100 mA at 1/4 s has been used. If one changes to the 500 mA statio, the appropriate exposure time for the same mAs us which of the following? A. 1/4 s B. 3/20 s C. 1/20 s D. 1/5 s E. 1/10 s

C. 1/20 s

A radiographic technique calls for 50 ms exposure, bu the exposure control has only fractional notation. Which of the following should be selected? A. 1/60 sec B. 1/40 sec C. 1/20 sec D. 1/10 sec E. 1/4 sec

C. 1/20 sec

If 60 Hz AC power is full-wave rectifier, output voltage consists of: A. 60 pulses per second B. 90 pulses per second C. 120 pulses per second D. 70% ripple E. Zero ripple

C. 120 pulses per second

A radiographic technique calls for a 400 mA, 1/20 sec exposure. What is the mAs? A. 5 mAs B. 10 mAs C. 20 mAs D. 40 mAs E. 80 mAs

C. 20 mAs

A filament transformer has a turn ratio of 1:20. What current must be supplied to the primary windings if 5 A is required by the filament? A. 125 mA B. 200 mA C. 250 mA D. 50 A E. 100 A

C. 250 mA

How many overlapping pulses are generated in 1 s for three-phase, six-pulse power? A. 60 B. 120 C. 360 D. 720 E. 2160

C. 360

Operation at 100 mA for 1 s results in which of the following? A. 6.3X10^16 electrons B. 6.3X10^17 electrons/s C. 6.3X10^17 electrons D. 6.3X10^18 electrons/s E. 6.3X10^18 electrons

C. 6.3X10^17 electrons

The current from a common household wall receptacle in the United States is: A. 50 Hz AC B. 50 Hz DC C. 60 Hz AC D. 60 Hz DC E. Constant potential

C. 60 Hz AC

Which of the following is used to determine the voltage before exposure? A. A filament transformer B. A postreading voltmeter C. A voltmeter D. A step-up transformer E. An autotransformer

C. A voltmeter

The autotransformer converts: A. Chemical energy to electrical energy B. Electric energy to chemical energy C. Electric energy to electric energy D. Magnetic energy to electric energy E. Mechanical energy to electric energy

C. Electric energy to electric energy

The autotransformer operates on the principle of: A. Coulomb's law B. Edison's law C. Faraday's law D. Newton's law E. Oersted's law

C. Faraday's law

An exposure technique of 100 mA at 100 ms compared with 50 mA at 50 ms results in: A. Eight times the total number of electrons B. Fewer projectile electrons C. Four times the total number of electrons D. Three times the total number of electrons E. Twice the total number of electrons

C. Four times the total number of electrons

Which of the following principles of rectification produces the maximum efficiency of x-ray production? A. Four-diode rectification B. Half-wave rectification C. High frequency rectification D. Self-rectification E. Two-diode rectification

C. High frequency rectification

A semiconductor rectifier: A. Has a heated anode B. Has a heated cathode C. Is a solid-state device D. Is an electromechanical device E. Is used only for mammography

C. Is a solid-state device

Taps on the windings of an autotransformer may be used to select which of the following? A. Exposure time B. Focal spot C. Line compensation D. mA E. Rectification

C. Line compensation

Concerning the transformers used in the x-ray circuit: A. The filament transformer is also an autotransformer B. The filament transformer usually is located in the console. C. The high-voltage transformer is a step-up device. D. They convert AC to DC E. They operate only on DC

C. The high-voltage transformer is a step-up device.

The filament transformer is designed: A. As a step-up transformer B. To operate on DC power C. With a turn ratio less than 1 D. With a turn ratio greater than 1 E. With an mA meter grounded to the center tap

C. With a turn ratio less than 1

A filament transformer has 800 primary windings and is supplied with 200 mA. If the secondary coil has 100 windings, what will be the secondary current be? A. 25 mA B. 100 mA C. 400 mA D. 1600 mA C. 3200 mA

D. 1600 mA

A radiographic technique calls for 86 kVP/ 200 mAs using the 800 mA station. What is the exposure time? A. 10 ms B. 25 ms C. 100 ms D. 200 ms E. 500 ms

D. 200 ms

There are 30 video frames each second for a fluoroscopic CRT dynamic image. What is the length for each frame? A. 1 ms B. 10 ms C. 16 ms D. 33 ms E. 60 ms

D. 33 ms

One coulomb per second (C/s) is equivalent to 1 A, and 1 C is equal to 6.3X10^18 electrons. Therefore, operation at 100 mA would result in a current of: A. 6.3X10^16 electrons B. 6.3X10^16 electrons/s C. 6.3X10^17 electrons D. 6.3X10^17 electrons/s E. 6.3X10^18 electrons

D. 6.3X10^17 electrons/s

The filament transformer in the previous question is supplied with 150 V to the primary side. What is the secondary voltage? A. 750 mV B. 3000 mV C. 1.5 V D. 7.5 V E. 30 V

D. 7.5 V

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? A. Autotransformer B. Exposure timer C. Filament transformer D. High-voltage transformer E. Rheostat

D. High-voltage transformer

The autotransformer can be used to do which of the following? A. Control exposure time B. Converts AC to DC C. Converts DC to AC D. Increase kVp E. Increase mA

D. Increase kVp

Which of the following is an advantage of three-phase power over single-phase power? A. Improved spatial resolution B. Increased kVp C. Increased mAs D. Increased x-ray intensity per mAs E. Lower capital cost

D. Increased x-ray intensity per mAs

The disadvantage of a self-rectified circuit is: A. Its complexity B. Its cost C. Its limitation of use to dental imaging systems D. Its limited exposure time E. Its requirement of DC power

D. Its limited exposure time

X-ray tube current is usually measured in which of the following? A. Amperes (A) B. Ampere-seconds (As) C. Microamperes (μA) D. Milliamperes (mA) E. Milliamperes-seconds (mAs)

D. Milliamperes (mA)

The control of exposure time is always: A. Automatically set B. Determined by kVp C. On the primary side of the autotransformer D. On the primary side of the high-voltage transformer E. On the secondary side of the filament circuit

D. On the primary side of the high-voltage transformer

The meter that monitors x-ray tube current is: A. Connected to the autotransformer B. Connected to the secondary side of the step-down transformer C. Grounded to the primary center tap of the step-up transformer D. Physically located on the control console E. The same as the filament current monitor.

D. Physically located on the control console

The design of fixed mA stations requires the use of which of the following? A. A centered-tapped meter B. DC power C. Major and minor taps D. Precision resistors E. Primary and secondary windings

D. Precision resistors

Full-wave rectification: A. Has less ripple compared with half-wave rectification B. Is one example of self-rectification C. Produces higher kVp than half-wave rectification D. Requires at least 4 rectifiers E. Requires at least twelve rectifiers

D. Requires at least 4 rectifiers

Which of the following is higher for a single-phase high-voltage generator than for a three-phase high voltage generator? A. kVp B. Purchase price C. Rotor speed D. Voltage ripple E. X-ray quality

D. Voltage ripple

The shortest exposure possible with three-phase equipment is 1 ms. What fraction of a second is that? A. 1/50 B. 1/100 C. 1/120 D. 1/500 E. 1/1000

E. 1/1000

Mammography sometimes requires exposures as long as 1.5 s. This is equivalent to which of the following? A. 15 ms B. 100 ms C. 150 ms D. 1000 ms E. 1500 ms

E. 1500 ms

The human eye cannot visualize faster than approximately five views each second. What is the integration time of the human eye? A. 1 ms B. 10 ms C. 20 ms D. 100 ms E. 200 ms

E. 200 ms

A filament current of 5 A is necessary for thermionic emission. What electron flow is this? A. 3.2X10^15 electrons/s B. 3.2X10^16 electrons/s C. 3.2X10^17 electrons/s D. 3.2X10^18 electrons/s E. 3.2X10^19 electrons/s

E. 3.2X10^19 electrons/s

With an autonomic exposure control (AEC) device: A. Exposures less than 100 ms are not possible B. It is not necessary to depress the exposure control C. The exposure stops automatically D. Technique selection is not necessary E. A backup timer is required

E. A backup timer is required

The main advantage of full-wave rectification over half-wave rectification is: A. Higher-energy x rays B. Higher kVp C. Higher mA D. Less voltage ripple E. A greater number of x-rays per cycle

E. A greater number of x-rays per cycle

The filament transformer is usually: A. A part of the autotransformer B. Located with the high-voltage generator C. An autotransformer D. Located in the operating console E. A step-down transformer

E. A step-down transformer

Near the p-n junction of a semiconductor diode, one will find: A. A filtered anode B. A heated anode C. A heated cathode D. A p type of material containing excess electrons E. An n type of material containing excess electrons

E. An n type of material containing excess electrons

Line compensation: A. Adjusts the line frequency to 60 hz B. Compensates for rectification C. Is necessary for proper exposure timing D. Is necessary to convert AC to DC E. Is required to stabilize voltage

E. Is required to stabilize voltage

An exposure of 1/10 s: A. At 50 mA is 50 mAs B. At 100 mA is 1000 mAs C. Is 120 ms D. Produces six pulses in full-wave rectification E. Produces twice as much radiation if full-wave rectified than if half-wave rectified

E. Produces twice as much radiation if full-wave rectified than if half-wave rectified

The output voltage from the autotransformer is: A. Always less than the input voltage B. Always more than the input voltage C. Fed directly to the rectifiers D. Inversely proportional to the turns ratio E. Proportional to the turns ratio

E. Proportional to the turns ratio

Power to the primary side of the high-voltage transformer comes from the: A. Filament transformer B. Line-voltage compensator C. Primary side of the autotransformer D. Rectifier E. Secondary side of the autotransformer

E. Secondary side of the autotransformer

Selection of kVp: A. Involves two series of autotransformers B. Requires rectified voltage C. Requires that constant voltage be supplied to the autotransformer D. Uses meters and switches that are at high kVp E. Uses the step-up transformer

E. Uses the step-up transformer

What is the approximate voltage ripple for, three-phase, six-pulse?

13%

What is the approximate voltage ripple for, self rectified?

100%

What is the approximate voltage ripple for, high frequency?

1%

What is the approximate voltage ripple for, full wave rectified?

100%