UNIT 2 – RT 244 MORE REVIEW QUESTIONS
CIRCUITRY – TOMOGRAPHY - EQUIPMENT
True/False
Indicate whether the sentence or statement is true or false.
____1.As two electrical charges move further apart, the force between them decreases proportionally to the inverse square of their separation.
____2.Electron flow and conventional current are equal in magnitude, yet opposite in direction.
____3.Because the human body is an infinite supply of electric charges, it is used for the reference of ground.
____4.The force between two charges is inversely proportional to the product of their magnitudes and directly proportional to the square of the distances between them.
____5.Objects can be electrified by induction.
____6.Induction is the process of electrical fields acting on one another with contact.
____7.Electrons flow from greatest potential difference to least potential difference.
____8.For potential difference to exist, there must be electron flow.
____9.As the length of a conductor increases, the resistance increases.
____10.The total resistance of a parallel circuit is always greater than the amount of the highest resistor.
____11.Magnetic lines of force are also referred to as flux lines.
____12.Coulomb’s Law can be applied to magnetism.
____13.Electromagnets are permanent magnets.
____14.Fleming's hand rules are based on electron flow.
____15.Mutual induction occurs when two coils are connected in series, causing current to flow in the secondary coil.
____16.An AC generator produces a current that is expressed mathematically as a sinusoidal wave.
____17.The apparent total resistance of an AC current is called impedance.
____18.As the length of a conductor increases, the resistance increases.
____19.Therapeutic equipment operates at much lower energies than diagnostic equipment.
____20.Therapy equipment operates at high voltages and low amperages.
____21.Floating tops can be moved when an electromagnetic brake is engaged.
____22.The telescoping column of the overhead suspension system controls horizontal movement.
____23.A head unit consists of a bucky tray and an x-ray tube.
____24.In the United States, the incoming line voltage to an x-ray unit is approximately 120 volts.
____25.The root mean square voltage of a single-phase sinusoidal wave is usually given as 70.7% of the peak voltage.
____26.During three-phase power, the overall potential difference drops to zero.
____27.The cathode is the negative side of the x-ray tube.
____28.The filament is set in the cathode assembly outside of the focusing cup.
____29.Electrons in the thermionic cloud are driven from cathode to anode with 100% efficiency.
____30.Most x-ray tubes have a dual-focus arrangement.
____31.To prolong x-ray tube life, the exposure switch should be partially depressed for a few seconds before complete depression occurs.
____32.Filament saturation occurs when the negative charge of the electron cloud opposes the emission of additional electrons from the filament.
____33.The faster the anode rotation, the better the heat dissipation.
____34.Like the cathode, the anode is comprised of a single metal called tungsten.
____35.The line-focus principle is used to reduce the actual area of the focal spot.
____36.When the target angle is less than 45°, the effective focal spot is smaller than the actual focal spot.
____37.As the anode target angle increases, the primary beam field size increases.
____38.In radiology, the term focal spot size refers to the effective focal spot.
____39.According to the anode heel effect, the radiation intensity is greater on the anode side.
____40.The entire cathode and anode assemblies are enclosed within the glass envelope.
____41.Off-focus radiation is of significantly lower energy than the primary beam itself.
____42.As the tomographic amplitude increases, the section thickness decreases.
____43.Since the advent of computed tomography and magnetic resonance imaging, tomographic procedures have increased in number.
____44.There is a direct relationship between distance from the fulcrum and blurring.
____45.Objects above and below the fulcrum are projected directly on the fulcrum.
____46.There is an inverse relationship between the tomographic amplitude and the section thickness.
____47.The exposure amplitude is always equal to or greater than the tomographic amplitude.
____48.Increased blurring causes decreased density.
____49.As the tomographic amplitude increases, blurring decreases.
____50.As the distance of the object from the fulcrum increases, blur decreases.
____51.The distance from the image receptor has a direct relationship to the blur width.
____52.Phantoms commonly occur during circular tomography.
____53.As the exposure angle increases, the section thickness increases.
____54.Complex tomographic motions require counter-rotation of the grid.
____55.During linear tomography, structures parallel to the motion streak.
____56.Tomography is most often used to localize objects that are difficult to see due to superimposed structures.
____57.Due to limitations caused by fixed time settings, all fine adjustments must be accomplished by variations of kVp.
Multiple Choice
Identify the letter of the choice that best completes the statement or answers the question.
____58.The resistance in a wire decreases as its diameter ____.
a. / increases / c. / remains the sameb. / decreases / d. / none of the above
____59.If the total resistance in a circuit is 9 ohms and the total voltage is 3 volts, the current is ____.
a. / 1/27 ampere / c. / 3 amperesb. / 1/3 ampere / d. / 27 amperes
____60.If a DC circuit is ____.
a. / in series, the currents are different for each component (e.g., resistors)b. / in series, the voltages are the same for each component
c. / in parallel, the currents are equal for all paths of the circuit
d. / in parallel, the voltages are equal for all paths of the circuit
____61.Current is ____.
a. / time/charge / c. / (charge)(time)b. / charge/time / d. / charge/time2
____62.Coulomb's Law of electrical forces is mathematically described as ____.
a. / F = q1q2/r2 / c. / F = q1q2/rb. / F = q/r2 / d. / F = q2/r
____63.A current of 2 amperes and a resistance of 8 ohms require what voltage in a circuit?
a. / 1/16 volt / c. / 4 voltsb. / 1/4 volt / d. / 16 volts
____64.When an electric current flows through a wire with resistance, energy is ____.
a. / liberated as x-rays / c. / liberated as lightb. / liberated as heat / d. / absorbed as heat
____65.Ohm's Law is mathematically described as ____.
a. / C = Q/V / c. / R = V/Ib. / L = -V/It / d. / V = I2R
____66.Electric potential is measured in ____.
a. / coulombs / c. / voltsb. / joules / d. / ohms
____67.Electric insulators ____.
a. / convert electrical energy into heat / c. / inhibit movement of electrical chargeb. / consist of materials like silicon / d. / permit movement of electrical charge
____68.If 20 volts of potential difference causes a current of 5 amperes, the resistance produced is ____.
a. / 1/100 ohm / c. / 4 ohmsb. / 1/4 ohm / d. / 100 ohms
____69.A volt is a measure of ____.
a. / random drift velocity / c. / currentb. / flow rate / d. / potential difference
____70.A charge would lose most of its energy when it passes through a ____.
a. / resistor / c. / generatorb. / battery / d. / all of the above
____71.If the distance between two electrical charges is doubled, the force between them is ____.
a. / decreased by 1/4 / c. / doubledb. / decreased by 1/2 / d. / quadrupled
____72.A formulation of power in a circuit with an EMF source and a resistor with a current is ____.
a. / P = IV / c. / P = I2Rb. / P = IR/V / d. / more than one of the above
____73.An ampere is ____.
a. / coulomb/sec / c. / (volt)(ohm)b. / (coulomb)(sec) / d. / ohm/volt
____74.Resistance is ____.
a. / the opposition to the flow of electronsb. / the opposition to the generation of electromotive force
c. / the location of storage of electrons
d. / measured in amperes
____75.The charge on each of two objects is doubled and they are moved twice as far apart. The force between them is ____.
a. / increased by a factor of 4 / c. / increased by a factor of 1/2b. / increased by a factor of 2 / d. / unchanged
____76.A circuit has a current of 2 amperes and a resistance of 4 ohms. The maximum power that can be delivered is ____.
a. / 16 watts / c. / 2 wattsb. / 8 watts / d. / 1/2 watt
____77.The unit of electrical power is ____.
a. / joule / c. / ampereb. / volt / d. / watt
____78.If 10 coulombs pass a point in 2 seconds, the current is ____.
a. / 0.20 amp / c. / 20 ampsb. / 5 amps / d. / 200 amps
____79.The electrons in an electrical current ____.
a. / all have the same velocityb. / flow from one end of the circuit to another
c. / have a net motion in the direction opposite to the conventional current flow
d. / none of the above
____80.In a battery circuit with several resistors of different values connected in series ____.
a. / the voltage drop is the same across all the resistorsb. / the current through each resistor is different
c. / the power dissipated through each resistor is the same
d. / none of the above
____81.If a conductor is positively charged, it ____.
a. / has too many electrons / c. / has more neutrons than electronsb. / is deficient in electrons / d. / is deficient in protons
____82.The mA is a unit of ____.
a. / EMF / c. / currentb. / voltage / d. / potential difference
____83.A magnetic field is produced by ____.
a. / electric charges at restb. / electric charges in motion
c. / permanent magnets only
d. / electric charges both at rest and in motion
____84.An alternately expanding and contracting magnetic field is produced by ____.
a. / a stationary magnet / c. / a batteryb. / a steady current flowing in a wire / d. / none of the above
____85.A diode electron tube ____.
a. / is used for amplification / c. / cannot reach saturationb. / has a negatively charged anode / d. / can be used for rectification
____86.The magnetic flux through a wire loop ____.
a. / requires a time varying magnetic fieldb. / is maximum when the plane of the loop is perpendicular to the magnetic field
c. / increases as the magnetic field decreases
d. / none of the above
____87.The charge carriers are considered to be a negative in a ____.
a. / diode / c. / N-type semiconductorb. / triode / d. / P-type semiconductor
____88.Electrons move southward in a vertical wire. The direction of the associated magnetic field directly around the wire is ____.
a. / clockwise / c. / in the direction of the electron flowb. / counter-clockwise / d. / opposite to the conventional current
____89.An induced current in a wire loop ____.
a. / results from a constant magnetic fluxb. / can result only from an alternately expanding and contracting magnetic field
c. / is in such a direction that its effects oppose the change producing it
d. / always decreases when the magnetic flux decreases
____90.The process of electrons being emitted from heated metallic surfaces is called ____.
a. / thermionic emission / c. / equilibriumb. / thermionic remission / d. / potential difference
____91.The magnitude felt by a moving charge through a magnetic field would be least if the charge were ____.
a. / moving directly into the magnetic fieldb. / moving directly away from the magnetic field
c. / moving at a right angle to the magnetic field
d. / both a and b
____92.A generator is a device that converts ____.
a. / electrical energy into heat energyb. / heat energy into electrical energy
c. / mechanical energy into electrical energy
d. / electrical energy into mechanical energy
____93.A simple DC generator has essentially the same construction as an AC generator except that a DC generator has ____.
a. / slip rings / c. / brushesb. / a commutator / d. / armature
____94.A rectifier ____.
a. / refers to a type of electromagnetic deviceb. / refers to a type of electromechanical device
c. / converts DC to AC
d. / converts AC to DC
____95.A motor is a device that converts ____.
a. / heat energy into electrical energyb. / electrical energy into mechanical energy
c. / electrical energy into heat energy
d. / mechanical energy into electrical energy
____96.A transformer with more secondary windings than primary windings ____.
a. / has a greater secondary voltage / c. / has a greater power output than inputb. / is a step-down transformer / d. / none of the above
____97.Which of the following is a component of a tube-type rectifier?
a. / filament / c. / primary windingsb. / magnetic core / d. / secondary windings
____98.A bar magnet and a wire loop move with the same linear velocity. What is the voltage induced in the wire?
a. / relative to the angle of incidence / c. / inversely proportional to the velocitiesb. / directly proportional to their velocities / d. / zero
____99.For a simple AC generator, the value of the induced voltage in the armature loop is maximum when the orientation of the armature as compared to the magnetic field is ____.
a. / at a node / c. / 90 degreesb. / 45 degrees / d. / 180 degrees
____100.How many times does an AC current change direction in a single minute?
a. / 1 / c. / 60b. / 2 / d. / 7,200
____101.The efficiency of a transformer is not affected by ____.
a. / eddy current loss / c. / hysteresis lossb. / power loss / d. / all of the above
____102.American generators operate at ____.
a. / 220 V / c. / 60 Hzb. / 120 AC / d. / 30 A
____103.A stator consists of ____.
a. / bars of copper around an iron core / c. / a rotorb. / commutator rings / d. / electromagnets
____104.Conventional current flows ____.
a. / from cathode to anodeb. / from anode to cathode
c. / in either direction
d. / in the same direction as the electron flow
____105.How many alterations in the direction of the current flow occur per second in a 60-Hz AC current?
a. / 20 / c. / 90b. / 60 / d. / 120
____106.At what point in the x-ray circuit is the rectification circuit located?
a. / between the semiconductors and the valve tubesb. / between the step-down transformer and the rheostat
c. / between the step-up transformer and the x-ray tube
d. / between the thermionic diode tubes and the x-ray machines
____107.Where is the stator of the anode induction motor located?
a. / inside the glass envelope but outside the rotorb. / outside the glass envelope and outside the rotor
c. / inside the glass envelope and inside the rotor
d. / outside the glass envelope but inside the rotor
____108.The exposure switch on an x-ray machine is intended to ____.
a. / initiate the exposureb. / terminate the exposure
c. / both initiate and terminate the exposure
d. / rotate the anode up to speed
____109.The exposure switch is found between the ____.
a. / incoming line and the circuit breakerb. / autotransformer and the timer circuit
c. / exposure switch and the step-up transformer
d. / incoming line and the step-down transformer
____110.The electrical device used to adjust the mA selection is the ____.
a. / autotransformer / c. / switchb. / stator / d. / variable resistor
____111.The time control is found between the ____.
a. / incoming line and the exposure switchb. / autotransformer and the timer circuit
c. / exposure switch and the step-up transformer
d. / incoming line and the step-down transformer
____112.The mA control is found between the ____.
a. / incoming line and the exposure switchb. / autotransformer and the timer circuit
c. / exposure switch and the step-up transformer
d. / incoming line and the step-down transformer
____113.The kVp control is found between the ____.
a. / incoming line and the exposure switchb. / autotransformer and the timer circuit
c. / exposure switch and the step-up transformer
d. / incoming line and the step-down transformer
____114.Medical x-ray units can be classified as ____.
a. / diagnostic / c. / fluoroscopicb. / therapeutic / d. / both a and b
____115.The diagnostic x-ray range is approximately ____.
a. / 10 to 1,200 mA / c. / 25 to 150 kVpb. / 0.001 to 10 seconds / d. / all of the above
____116.The advantage of a curved top radiographic table is ____.
a. / positioning accuracy in oblique and lateral positionsb. / level support of the radiographic film
c. / easy clean up
d. / a smaller object image distance
____117.The Bucky tray consists of ____.
a. / a moving 14 × 17 inch grid / c. / a moving 17 × 17 inch gridb. / a stationary 14 × 17 inch grid / d. / a stationary 17 × 17 inch grid
____118.Radiographic table tops may be ____.
a. / floating / c. / motor drivenb. / stationary / d. / all of the above
____119.Radiographic rooms equipped with a tilting table are primarily designed for performing ____ procedures.
a. / diagnostic / c. / fluoroscopicb. / angiographic / d. / both a and c
____120.The height of the average radiographic table top to the floor is ____ inches.
a. / 25 / c. / 60b. / 40 / d. / 120
____121.Tube suspension systems include ____.
a. / overhead / c. / C-armb. / mobile / d. / all of the above
____122.Which tube suspension system offers the greatest multidirectional movement?
a. / overhead tube suspension system / c. / floor tube suspension systemb. / floor-to-ceiling tube suspension system / d. / mobile tube suspension system
____123.The incoming line current is supplied ____.
a. / in the form of a three-phase power cycleb. / in the form of a single-phase power cycle
c. / as a direct current
d. / at approximately 60 volts
____124.Nearly all x-ray equipment operates from an incoming line of ____.
a. / 210 V / c. / 120 Hzb. / 120 AC / d. / 210 A
____125.When full-wave rectification is applied to three-phase current, a ____ ripple is produced.
a. / wye / c. / voltageb. / star / d. / delta
____126.A three-phase, rectified current produces a voltage ripple of ____ pulses per Hz.
a. / 3 / c. / 9b. / 6 / d. / 24
____127.A star or delta connection is used to ____.
a. / tap a single phase of power / c. / produce rectificationb. / combine three-phase current / d. / drop the wave peak to zero
____128.Which condition is needed to produce an x-ray?
a. / a source of electrons / c. / a large potential differenceb. / a vacuum / d. / all of the above
____129.The function of the cathode is to produce ____.
a. / a focal point / c. / a thermionic cloudb. / an electrical connection to the rectifier / d. / a grounding effect
____130.Each of the following is a part of the cathode assembly except the ____.
a. / filament / c. / focusing cupb. / stator / d. / associated wiring
____131.Each of the following is a material of choice for the filament except ____.
a. / copper / c. / rheniumb. / tungsten / d. / molybdenum
____132.Filament materials are chosen for their ____.
a. / low melting points / c. / ability to vaporize easilyb. / high melting points / d. / high boiling points
____133.Which of the following would affect the production of a thermionic cloud?
a. / filament diameter / c. / filament temperatureb. / filament length / d. / all of the above
____134.A filament may break due to ____.
a. / evaporation / c. / increased sensitivityb. / deposition / d. / vaporization
____135.Driving the thermionic cloud from the cathode to the anode requires ____.
a. / a large potential difference / c. / a large amperageb. / a small voltage / d. / a small amperage
____136.Production of the thermionic cloud requires ____.
a. / kilovoltage / c. / amperageb. / resistance / d. / more than one of the above
____137.The focusing cup has a/an ____ charge.
a. / neutral / c. / positiveb. / atomic / d. / negative
____138.As more and more electrons build up in the area of the filament, their negative charges oppose the emission of additional electrons. This phenomenon is known as ____.
a. / thermionic emission / c. / space charge effectb. / biased cloud formation / d. / current saturation
____139.X-ray photon production occurs at the ____.
a. / anode / c. / filamentb. / cathode / d. / stator
____140.Tungsten is the metal of choice for the source of x-ray photons because of its ____.
a. / high atomic number / c. / low mass numberb. / low melting point / d. / all of the above
____141.Pitting of the anode commonly occurs ____.
a. / when the unit is not warmed-up properlyb. / when the anode is off focus
c. / with extended use
d. / when the kilovoltage is too high
____142.Melting of the anode commonly occurs ____.
a. / when the unit is not warmed up properlyb. / with extended use
c. / when the kilovoltage is too high
d. / when the stator fails and the rotor ceases to turn
____143.Cracking of the anode commonly occurs ____.
a. / when the kilovoltage is too highb. / when the anode is off focus
c. / with extended use
____144.The exact point in the x-ray unit where photons are created is the ____.
a. / focusing cup / c. / statorb. / focal spot / d. / rotor
____145.The physical area of the focal track affected by the electron beam is the ____.
a. / effective focal spot / c. / actual focal spotb. / effective focal track / d. / all of the above
____146.The area of the focal spot that is projected out of the tube towards the object being radiographed is the ____.