Radiography - Ch. 5
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81 terms
Terms | Definitions |
|---|---|
 primary function of an x-ray imaging system is to convert _______ energy into _______ energy | electric; electromagnetic |
| unlike charges _______; like charges _______ | attract; repel |
| a conversion takes place in the x-ray tube where most electric energy is transformed into _______, some of it into _______ | heat; x-rays |
| matter has mass and _______ equivalence; matter also may have _______ charge | energy; electric |
| _______ is the study of stationary electric charges | electrostatics |
| coulomb's law | electrostatic force (F) is directly proportional to the product of the electrostatic charges (Qa & Qb) and inversely proportional to the square of the distance between them |
| fundamental unit of electric charge | coulomb (C) |
| the force of attraction between unlike charges or repulsion between like charges is due to the _______ field; it is called an _______ force | electric; electrostatic |
| electric charge of a conductor is concentrated along the _______ of the surface | sharpest curvature |
| electrons often are _______ from the outermost shell of one atom to another | free to travel |
| protons are _______ inside the nucleus | fixed |
| the higher the voltage, the greater is the _______ to do work | potential |
| an object is said to be _______ if it has too few or too many electrons | electrified |
| coulomb's law equation | F = k QaQb divided by d(squared) |
| any substance through which electrons flow easily | conductor |
| x-ray imaging systems usually requires _______ V or higher | 220 |
| unit of electric potential | volt (V) |
| electric resistance is measured in _______ | ohms (upside down horseshoe) |
| electric potential is measured in _______ | volts (V) |
| ohm's law | the voltage across the total circuit or any portion of the circuit is equal to the current times the resistance |
| in a _______ circuit, all circuit elements are connected in a line along the same conductor | series |
| any material that does not allow electron flow | insulator |
| a material that under some conditions behaves as an insulator and in other conditions behaves as a conductor | semiconductor |
| the property of some materials to exhibit no resistance below a critical temperature | superconductivity |
| a _______ circuit contains elements that are connected at their ends rather than lying in a line along a conductor | parallel |
| the study of electric charges in motion | electrodynamics |
| electric charge distribution is _______ throughout or on the surface | uniform |
| waveform of AC is a _______ curve | sine |
| electric power is measured in _______ | watts (W) |
| increasing electric resistance results in a _______ electric current | reduced |
| ohm's law formula | V = IR .... volts = amperes times ohms .... electric potential = electric current times electric resistance |
| if electrons flow in one direction along the conductor, the electric current is called _______ current | direct (DC) |
| current drawn out in a graph | waveform |
| rules for parallel circuits: the sum of the currents through each circuit element is ... | equal to the total circuit current |
| DC is represented by a _______ line | horizontal |
| rules for series circuits: the current through each circuit element is the same and is ... | equal to the total circuit current |
| current where electrons oscillate back and forth is called _______ current | alternating (AC) |
| rules for parallel circuits: the total resistance is the inverse of the sum of ... | the reciprocals of each individual resistance |
| rules for series circuits: the total resistance is equal to ... | the sum of the individual resistances |
| magnets are classified according to the _______ of the magnetic property | origin |
| rules for parallel circuits: the voltage across each circuit element is the same and is ... | equal to the total circuit voltage |
| unit for current | amperes (A) |
| rules for series circuits: the sum of the voltages across each circuit element is ... | equal to the total circuit voltage |
| any charged particle in motion creates a _______ field | magnetic |
| the lines of a magnetic field are always _______ loops | closed |
| the magentic force is proportional to the _______ of the magnetic pole strengths _______ by the square of the distance between them | product; divided |
| materials that are unaffected when brought into a magnetic field | nonmagnetic (wood, glass) |
| all _______ can be classified according to the manner in which it interacts wtih an external magnetic field | matter |
| electric power formula | P=IV (power in watts = current in amperes times electric potential in volts) |
| materials that are weakly repelled by either magnetic pole | diamagnetic (water, plastic) |
| materials that lie somewhere between ferromagnetic and nonmagnetic; slightly attracted to a magnet and loosely influenced by an external magnetic field | paramagnetic (gadolinium, contrast agents in MRI) |
| ferromagnetic objects can be made into magnets by _______ | induction |
| materials that are strongly attracted by a magnet and usually can be permanently magnetized | ferromagnetic (iron, cobalt, nickle) |
| if the distance between two bar magnets is halved, the magnetic force increases by _______ times | four |
| the SI unit of magnetic field strength | tesla (T) |
| any charge in motion induces a _______ field | magnetic |
| using zinc and copper plates, he came up with the first battery | Volta (the voltaic pile) |
| faraday's law: the magnitude of the induced current depends on: the _______ of the magnetic field | strength |
| any device that converts some form of energy directly into electric energy is said to be a source of _______ force | electromotive |
| a coild of wire is called a _______ | solenoid |
| electric potential is measured in ... | units of joule per coulomb, or volt |
| an electromagnet is a current-carrying coil of wire wrapped around an _______ core, which intensifies the induced magnetic field | iron |
| the net effect of an electric generator is to convert _______ energy into _______ energy | mechanical into electric |
| transformer law | Vs / Vp = Ns / Np (voltage of secondary circuit divided by voltage of primary circuit = windings of the secondary coil divided by windings of primary coil) |
| faraday's law: the magnitude of the induced current depends on: the _______ of the magnetic field as it moves past the conductor | velocity |
| faraday's law: the magnitude of the induced current depends on: the _______ of turns in the conductor | number |
| an _______ motor powers the rotating anode of the x-ray tube | induction |
| varying magnetic field intensity induces an _______ current | electric |
| faraday's law: the magnitude of the induced current depends on: the _______ of the conductor to the magnetic field | angle |
| electric motor changes _______ energy into _______ energy | electric into mechanical |
| transformer with a turns ratio greater than 1 | step-up transformer |
| electromagnetic induction: an electric current is induced in a circuit if some part of that circuit is in a _______ magnetic field | changing |
| transformer's turns ratio | Ns / Np (windings of the seconday coil divided by windings of primary coil) |
| transformer where current on secondary side is smaller than current on primary side | step-up transformer (Is < Ip) |
| transformer that confines even more of the magnetic field lines of the primary winding because the secondary winding is wrapped around it and there are essentially two closed cores: more efficient than closed-core | shell-type transformer (sideways 8 with coil along middle) |
| changes the intensity of alternating voltage and current | transformer (must be AC) |
| type of transformer built about a square core of ferromagnetic material | closed-core (square with primary coil on one side and secondary coil on the other) |
| transformer with a turns ratio less than 1 | step-down transformer |
| effect of transformer law effect on current (formula) | Is / Ip = Np / Ns or Is / Ip = Vp / Vs |
| transformer where current on secondary side is larger than the primary current | step-down transformer (Is > Ip) |
| transformer that condists of an iron core with only one winding of wire about it; this single winding acts as both the primary and the secondary winding | autotransformer (single stick with coiling wire) |
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