Term
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Definition
| Process of electron charges being added to or subtracted from an object |
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Term
| The earth is a zero or ______... basically, it has an infinite number of + and - charges in equal distribtuion, and is considered neutral |
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Definition
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Term
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Definition
1. Law of repulsion and attraction
2. Inverse square law
3. Distribution
4. Concentration
5. Movement |
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Term
| Law of repulsion & attraction |
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Definition
| Attraction; like charges repel, unlike charges attract |
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Term
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Definition
| Force between 2 objects is inversely proportional to the square of the distance between them |
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Term
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Definition
| Charges reside on the external surfaces of conductors and equally throughout nonconductors. This happens b/c of the law of like charges (- and - don't attract) |
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Term
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Definition
| The greatest concentration of charge will be on the surface where curvature is sharpest. If enough electrons congregate, they can ionize air or discharge to a point of lower concentration. This is why the x-ray tube has a coiled filament. |
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Term
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Definition
| Only negative charges move along solid conductors, b/c the electrons outside the nucleus are easily moved along |
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Term
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Definition
| One object is rubbed against another, resulting in electrons traveling from one object to the next. (Just like rubbing a balloon on someone's hair) |
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Term
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Definition
| Two objects touch, permitting electrons to move from one to the other. A friction interaction occurs when dragging feet along carpet, distributing electrons over your entire body. When you touch an object with a positive charge, a static discharge occurs, usually resulting in light photon distribution. |
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Term
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Definition
| Used in the operation of electronic devices. Process of electrical fields acting on one another without contact. |
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Term
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Definition
| Electrons that are moving in predominantly the same directions. many conditions affect the influence of electric current motion. |
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Term
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Definition
| A space from which air has been removed. X-rays are produced inside a cavuum in the x-ray tube. This prevents electrons passing from cathode to anode from interacting with air to slow them down. |
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Term
| Some gasses promote electron flow (from + to -) such as______ |
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Definition
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Term
| metallic conductors such as ______ ______ are the most common pathways provided for movement of electrical current. When thinking of electrical current, think of a tube filled with balls. |
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Definition
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Term
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Definition
Are materials that faciitate electron flow.
Examples are metals such as copper and aluminum, which tyoucally have one valence electron. |
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Term
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Definition
| Non-conducting materials; rubber, glass, plastic, white nervous tissue (myelinated), typically have their valence shells full or nearly full. |
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Term
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Definition
| Have the ability to either conduct electricity or insulate under certain conditions; Silicon, germanium |
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Term
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Definition
| Pathway (commonly copper wire) that permits electrons to move in a complete circle from their cource, though resisiting electrical devices and back to the source. |
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Term
| Sources that can cause current flow include: |
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Definition
1. Batteries
2. Generators
3. Solar concerters
4. Atomic reactors |
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Term
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Definition
| Which convert chemical energy to electrical |
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Term
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Definition
| Convert mechanical energy to electrical |
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Term
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Definition
| Convert solar photons to electrical energy |
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Term
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Definition
| Convert nuclear energy to electrical energy |
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Term
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Definition
| Electrons will move from highest concentration to lowest concentration |
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Term
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Definition
| This of as the quantity of electrons flowing within a given amount of time (we use seconds and milliseconds). Measured in Ampers. We adjust the mA at the console to vary the amount of electronswe boil off at the cathode end of the tube, which will eventualy result in quantity of x-ray photons after interaction with the rotating anode. |
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Term
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Definition
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Term
| Force/ strength/ potential difference |
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Definition
The difference in number of electrons in excess at one end of the circuit and deficiency at the other end (high concentration to low).
Potential difference describes the force or strength of electron flow; measured in volts |
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Term
| As current flows along the circuit, __________ decreases as electrons get closer to the side of deficiency |
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Definition
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Term
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Definition
| Amount of opposition to current within the circuit, measured in ohms |
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Term
| Resistance and length of a conductor are ___________. The longer the wire, the more resisitance it has. |
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Definition
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Term
| Resistance and diameter of the conductor are _______ proportional. As the diameter increases, resistance decreases (like water through a garden hose). |
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Definition
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Term
| Heat varies in its relationship with __________. |
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Definition
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Term
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Definition
| The current along a conductor is proportional to the potential difference (force) |
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Term
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Definition
V = IR
V
_______
I X R
V = potential difference in Volts (force)
I = current in Ampters
R = resistance in Ohms
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Term
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Definition
| Sends electrons through carious resistance devices by linking them one after another |
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Term
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Definition
| Provides each resistor with an individual branch |
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Term
Parallel circuits offer less resistance to electrical current if all factors are the same, they are not broken when a single resistor is interrupted (as when a ligh bulb burns out).
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Definition
| Christmas lights in series circuits do this. If the lights are on a parallel circuit, all other lights remain on. |
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Term
| Parellel circuits operate with greater current when all other factors are the same, which can be a disadvantage due to _________. Circuit breakers or fuses are installed which interrupt current when a certain temp is reached. Circuit breakers flip up and can be reset, while fuses melt and are not re-usable. |
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Definition
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Term
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Definition
| Can be applied as a resistor which allows manual fluctuation of boltage and amperage (volume knob on stereo). The disadvantage is the heat produced as a byproduct of manipulation, and thye are not very useful in high voltage circuits. |
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Term
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Definition
Total amount of power used in an electric circuit
P
____
I X R
P = power in watts
I = current/ amperes
R = Ohms/ resistance |
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Term
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Definition
| Occurs when materials have the ability to attract iron (or ferrous metals). When a charged particle is in motion, a magnetic force field perpendicular to the motion will be created. |
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Term
| Lines of force, lines of flux, or magnetic fields |
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Definition
| Forced fields created from magnets. |
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Term
| When outside a magnet, lines of force flow |
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Definition
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Term
| When inside a magent, lines of force flow |
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Definition
| From S to N (and never intersect) |
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Term
| The stronger the magnetic field, the greater number of _____________? |
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Definition
| Number of lines (or flux density) |
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Term
| The SI unit for magnetic flux |
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Definition
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Term
| Units for magnetic flux density are |
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Definition
| Tesla (T) and the Gauss (G) |
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Term
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Definition
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Term
| Magnets are classified by what type of production? |
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Definition
1. Natural magnet
2. Artificial permanent magnet
3. Electromagnet |
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Term
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Definition
Occur over time when natural iron forms within the earth
(Iodestone) |
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Term
| Artificial permanent magnet |
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Definition
Manufactured from a composition of metals which hold permanent charges
(Alnico- aluminum, nickel, colbolt) |
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Term
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Definition
| Temporary magnets produced by moving electric current |
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Term
| Three pertinent laws of magnetism |
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Definition
1. Laws of repulsion & attraction
2. Inverse square law
3. Magnetic poles |
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Term
| Law of repulsion & attraction |
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Definition
| Like poles repel, unlike poles attract. Also, lines of force moving in the same direction repel, and moving in opposite directions attract |
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Term
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Definition
| Intensity of magnetic force is inversely proportional to the square of the distance between them |
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Term
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Definition
Every magnet has a north and a south pole. No matter how many times it is divided, it maintains the poles.
(dipole) |
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Term
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Definition
| Can be achieved when a nonmagnetized metal temporarily aligns its poles with nearby lines of force from a magnet. Once that magnet is taken away, the poles slowly return after a period of time to a random magnet |
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Term
| Classifications of magnetic materials: |
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Definition
a. Permeability
b. Retentivity
1. Ferromagnetic
2. Paramagnetic
3. Diamagnetic
4. Nonmagnetic |
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Term
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Definition
| The ease at which material can be magnetized |
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Term
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Definition
| Ability of material to stay magnetized |
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Term
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Definition
Ferrous metals which are highly permeable and greatly susceptible to induction
(iron, cobalt, nickel) |
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Term
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Definition
Low permeability and weak attraction to magnetic fields
(Platinum and aluminum) |
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Term
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Definition
Weakly repelled by all magnetic fields including noth and south poles
(beryllium, bismuth, lead, water) |
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Term
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Definition
Not affected by magnetic fields and cannot be magnetized. These materials are formed by ionic or covalent bonds which eliminates their electrons to move freely along a magnetic force
(wood, glass, rubber, plastic) |
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Term
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Definition
| Electricity and magnetism |
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Term
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Definition
| Is created when current flows through a coiled wire. The strongest magnetic force will be inside the coil. |
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Term
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Definition
| Is made of solenoid with an iron core |
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Term
| The strength of solenoids and electromagnets is determined by? |
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Definition
-The number of loops of wire
-the currect strength to the wire
-and the permeability of the core |
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Term
| If electric current is removed from a solenoid or electromagnet, what will happen? |
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Definition
| All magnetic properties disappear |
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Term
| Factors influencing effectiveness of solenoids or electromagnets include: |
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Definition
1. Diameter of the coil
2. Length
3. Current passing along the coil
*Longer soleniod/electromagnet = stronger |
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Term
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Definition
| Occurs when two coilds are placed in proximitity and a varying current supplied to the first coil induces a similar flow in the second coil |
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Term
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Definition
| Device that functions to convert mechanical energy to electrical energy. Depending on the type of generator, AC or DC can be produced |
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Term
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Definition
AC= alternating current
DC= direct current |
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Term
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Definition
| A device that is supplied with electrical current to produce mechanical motion |
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Term
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Definition
| Composed of two coils placed near one another (w/o an electrical connection), that operates by mutual induction. The number of turns in the primary coil is different from the number of turns in the secondary coil. |
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Term
| If there are more coils in the secondary transformer? |
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Definition
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Term
| If there are more coils in the primary, what transformer is it? |
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Definition
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Term
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Definition
All transformers must operate on AC. Factors effecting efficiency of transformers in x-ray equipment
1. Copper loss
2. Hysterisis loss
3. Eddy current loss |
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Term
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Definition
| The inherent resistance to current flows found in all conductors that results in heat generation. Large diameter high-voltage wire is used to compensate for this |
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Term
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Definition
| Occurs as the changing current used with AC reverse magnetic fields back and forth, producing resistance |
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Term
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Definition
| Currents that offpose the magnetic field which is inducing them |
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Term
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Definition
| Operate on self induction, primary and secondary coils are wrapped around the same core, and these are used to make specific voltage selections along the coil |
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Term
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Definition
| Device that can accumulate and store an electrical charge |
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Term
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Definition
| X-ray tubes operate best using direct currents, but the transformers operate on AC. That's where rectifiers come on; AC is changed to pulsating DC |
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Term
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Definition
| The boiling off of electrons at the cathode end of the tube. With AC, magnetic poles can change, which would cause lots of problems if electrons went toward the cathode rather than the anode |
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Term
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Definition
| This is AC on the secondary side of high voltage step-up transformer. Only the positive portion of the wave is useful in the x-ray tube, cannot be applied yet |
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Term
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Definition
| The rectifier does not conduct current during the negative portion of the wave, and current can not be safe to administer to the x-ray tube. The output of half-wave rectification results in a loss or waste of half the power supply, and results in 60 x-ray pulses/sec. These contain two diodes (or rectifiers) |
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Term
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Definition
| Uses four diodes and reverses the negative wave from AC, making the output voltage to the x-ray tube always positive. This results in 120 pulses per second with all voltage useful. |
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Term
| All modern x-ray equipment uses full-wave rectification, which results in ? |
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Definition
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Term
| Most common form of transformer is the? |
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Definition
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