Physics Exam 2

The flow of 1 C/s in a conductor is equal to:

1 A

1 A is equal to:

1 C/s

A fluoroscope is operated at 95 kVp, 2mA. What is its power consumption? (in W)

190 W

An x-ray imaging system has a 30 kW generator. If the max tube voltage is 150 kV, what is the available tube current? (in mA)

200 mA

An L-shell electron (binding energy 26 keV) is removed from an atom that has M-shell binding energy of 4 keV and N-shell binding energy of 1 keV. If a free electron fils the vacancy in the L-shell, characteristic x-ray produced will have energy of:

26 keV

How many electrons are in 1 C?

6.3x 10^18

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

How are x-ray tube voltages measured? A. Kilovolt B. Megavolt C. Microvolt D. Millivolt E. Volt

A. Kilovolt

The shift of the characteristic x-ray spectrum to higher energy occurs because of:

An increase in target atomic number

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

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

Which of the following is a unit of mass? A. Joule B. Kilogram C. mrad D. Pound E. Volt

B. Kilogram

Useful characteristic x-rays are produced in tungsten:

By removal of a K shell electron

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 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

Energy is defined as: A. A force exerted by a body B. Anything that occupies space and has shape C. The ability to do work D. The degree of gravity E. The quantity of matter

C. The ability to do work

The primary purpose of the glass envelope of an x-ray tube is? A) control leakage radiation B) Cool tube C) ensure against electric shock D) provide a vacuum

D) provide a vacuum

What is produced when the projectile electron excites an outer-shell electron

Heat

The kinetic energy of the projectile electron in an x-ray tube:

Is about 1% efficient in production of x-rays

Electricity is purchased on basis of the kilowatt hours one consumes. The kilowatt hour also can express the unit:

Joule (kg⋅m2/s2)

If mass is expressed in kilograms and velocity in meters per second, kinetic energy will be expressed in:

Joules

The unit of electrostatic force is the:

Newton

The unit of electric potential is the:

Volt

The unit mAs could be expressed as: a. coulombs b. coulombs/second c. unit of electrical current d. unit of electrical force e. is electrons/second

a. coulombs

Which of the following is normally measured in volts? a. electric potential b. electromagnetic force c. electromagnetic potential d. electromagnetic radiation e. electrostatic force

a. electric potential

The control of focal spot size depends on: a. the filament that is 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 transformer

a. the filament that is energized

As the anode target angle increases: a.) Effective focal-spot size increases. b.) Heel effect becomes more pronounced. c.) kVp increases. d.) Radiation intensity on the central ray increases. e.) Target rotating speed increases.

a.) Effective focal-spot size increases.

Tungsten is the choice material for x-ray anodes because of its: a.) High atomic number. b.) High rpm. c.) High x-ray intensity. d.) Low atomic number. e.) Low rpm.

a.) High atomic number.

Necessary properties of X-ray target material include which of the following? a.) High melting point. b.) High rotation speed. c.) Low atomic number. d.) Low coefficient of friction. e.) High electrical resistance.

a.) High melting point.

Which of the following is an advantage of the rotating anode tube over the stationary anode tube? a.) Higher heat capacity. b.) Higher kVp capacity. c.) Longer exposure time. d.) Reduced heel effect. e.) The line-focus principle.

a.) Higher heat capacity.

1 Amp = a. 1 C b. 1 C/s c. 1 J/C d. 1 Js/C^2

b. 1 C/s

To find volts you would multiple: a. VxR b. IxR c. PxR d. PxI

b. IxR

Power can be expressed in units of: a. C/s b. J/s c. J/C d. Js/C^2

b. J/s

Which of the following is a unit of energy? a. Gray b. Joule c. Newton d. Rad e. Sievert

b. Joule

Which of the following target angles is characteristic of a rotating anode x-ray tube? a.) 1 degree b.) 10 degrees c.) 20 degrees d.) 50 degrees e.) 100 degrees

b.) 10 degrees

A diagnostic x-ray tube is an example of which of the following? a.) Cathode b.) Diode c.) Tetrode d.) Anode e.) Electrode

b.) Diode

The cathode beam of an x-ray tube is the: a.) Current that heats the filament. b.) Focused electron beam within the tube. c.) Off-focus radiation. d.) Primary x-ray beam. e.) secondary radiation.

b.) Focused electron beam within the tube.

The large filament is used during radiography when the head load is: a.) High, and visibility of detail is important. b.) High, and visibility of detail is less important. c.) Low, and high kVp is required. d.) Low, and visibility of detail is important. e.) Low, and visibility of detail is less important.

b.) High, and visibility of detail is less important.

1 volt = a. 1 C b. 1 C/s c. 1 J/C d. 1 Js/C^2

c. 1 J/C

The distinct difference between alternating current (AC) and direct current (DC) is that: a. DC can attain higher current b. dC can attain higher voltage c. DC electron flow in one direction d. DC electron flow varies in amplitude e. DC has higher electrical resistance

c. DC electron flow in one direction

To find power you would multiple: a. VxR b. IxR c. IxV

c. IxV

Which of the following equations can be used for calculating power? a. P= I^2V b. P=IR c. P= IV d. p= VR e. P= V/R

c. P= IV

Three principal parts of an x-ray imaging system: a. anode, cathode, and focusing cup b. anode, cathode, and high-voltage generator c. x-ray tube, control console, and image generator d. x-ray tube, high-voltage generator, and image receptor

c. x-ray tube, control console, and image generator

The x-ray tube current: a.) Controls x-ray energy. b.) Flows through both filaments at the same time. c.) Is controlled by the filament current. d.) Is the current that flows through the filament. e.) Usually varies from 50 to 1000 A.

c.) Is controlled by the filament current.

The cathode is: a.) A diode. b.) Designed to supply heat. c.) One of the two parts of a diode. d.) Part of the target. e.) Positively charged.

c.) One of the two parts of a diode.

The effective focal spot is: a.) Larger than the actual focal spot. b.) Largest on the anode side of the central axis. c.) Smaller than the actual focal spot. d.) Smallest on the cathode side of the central axis. e.) The same size as the actual focal spot.

c.) Smaller than the actual focal spot.

The unit of electrostatic charge is the:

coulomb

Resistance is expressed by which units: a. 1 C b. 1 C/s c. 1 J/C d. 1 Js/C^2

d. 1 Js/C^2

Kinetic energy (KE) is directly proportional to: a. A vector quantity. b. Acceleration. c. Force. d. Mass. e. Velocity.

d. Mass.

Which of the following is the primary method of heat dissipation from the anode of an x-ray tube? a. Conduction b. Convection c. Convention d. Radiation e. Reduction

d. Radiation

In electrodynamics hich of the following is a correct expression: a. I=Qt b. R=I^2V c. R=IV d. V=IR e. V=I/R

d. V=IR

X-ray tube current is usually measured in which if the following? a. Amps (A) b. Amps x seconds (As) c. microamps (uA) d. miliapms (mA) e. miliapms x sec (mAs)

d. miliapms (mA)

In a series circuit: a. Omh's law fails b. only three circuit elements are allowed c. the total current is the sum of the individual resistance d. the total resistance is the sum of the individual resistances e. the voltage drop across each circuit element is the same

d. the total resistance is the sum of the individual resistances

Rotating anode x-ray tubes: a.) Have a copper target embedded in a tungsten anode. b.) Have a tungsten target embedded in a copper anode. c.) Have target angles that are less than 10 degrees. d.) Incorporate the line-focus principle. e.) Produce higher energy x-rays.

d.) Incorporate the line-focus principle.

X-ray tube current: a.) Depends on exposure time. b.) Depends on voltage. c.) Increases when the kVp is decreased. d.) Is measured in milliamperes rather than amperes. e.) Is zero when filament current is above thermionic emission.

d.) Is measured in milliamperes rather than amperes.

The focusing cup: a.) Is on the positive side of the x-ray tube. b.) Is slightly positive with respect to the filament. c.) Is the grid in a grid-controlled x-ray tube. d.) Is usually made of thoriated tungsten. e.) Selects the filament.

d.) Is usually made of thoriated tungsten.

In most x-ray tubes, there are two filaments to: a.) Ensure saturation current. b.) Produce higher energy x-rays. c.) Provide two electrodes. d.) Provide two focal spots. e.) Reduce space charge effects.

d.) Provide two focal spots

The main reason for using the line-focus principle is to: a.) Increase heat capacity. b.) Increase x-ray intensity. c.) Reduce exposure time. d.) Reduce focal-spot size. e.) Reduce heel effect.

d.) Reduce focal spot size.

The heel effect: a.) Is more pronounced when large target angles are used. b.) Is reduced with a focusing cup. c.) Occurs only with rotating anode x-ray tubes. d.) Requires that the cathode be positioned to the thicker anatomy. e.) Suggests that the cathode be up during posteroanterior (PA) chest radiography.

d.) Requires that the cathode be positioned to the thicker anatomy.

Small target angles result in which of the following? a.) Better collimation. b.) Increased heat capacity. c.) Less heel effect. d.) Small focal-spot size. e.) Small space charge.

d.) Small focal-spot size.

X-ray intensity is higher on the cathode side than on the anode side because of which of the following? a.) The focusing cup. b.) The line-focus principle. c.) The space charge effect. d.) X-ray absorption in the anode. e.) X-ray deflection from the anode.

d.) X-ray absorption in the anode.

The unit of electric power is the: a.Hertz b. Joule c. Newton d. Volt e. Watt

e. Watt

Molybdenum is used for anode stem material because of which of the following? a.) It has a high atomic number. b.) It has a shiny surface and reflects electrons well. c.) It has longer life. d.) It is a good heat conductor. e.) It is a poor thermal conductor.

e.) It is a poor thermal conductor.

The heel effect occurs because of: a.) A focusing cup. b.) Reduced tube current. c.) The shape charge effect. d.) The shape of the filament. e.) X-ray absorption in the anode.

e.) X-ray absorption in the anode.

milliampere seconds (mAs) is a unit of:

electrostatic charge

x-ray beam quality (energy) is primarily determined by: a. focal spot size b. filament current c. x-ray tube current d. filament voltage

filament voltage

Ohm's law states that:

the electric potential is the product of current and resistance

What does the inverse square law state?

the intensity of the beam is inversely proportional to the square of the distance from the source

What is not affected by electrostatically charged matter?

x-rays