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131 Phsyics
Radiography Physics 131
| Question | Answer |
|---|---|
| Minimum response time of the automatic exposure control is : 1)time required to energize, 2)Shortest possible exposure time, 3)function to prevent over exposure, 4)protect from excessive heat. | SHORTEST POSSIBLE EXPOSURE TIME |
| What devices converts mechanical energy into electrical energy: | GENERATOR |
| Which galvanometer must be connected in parallel circuit? Filament ammeter, milliampmeter, voltmeter, rectifier | VOLTMETER |
| Placing an iron core into a current carrying coil of wire(solenoid) would turn the device into what | Electromagnet |
| A current carrying coil of wire is known as what | Solenoid |
| What is the purpose of an electric motor | To convert electricity into mechanical energy |
| What is the purpose of an electric generator | To convert mechanical energy into electricity |
| A magnetic field is created any time what type of particle is in motion | A charge particle |
| An electric current is induced in a circuit if some part of that circuit is in what type of magnetic field | Changing |
| What are the four factors of Faraday's law | The velocity(speed) of the magnetic field to the conductor, the magnetic field strength, the angle of the conductor to the magnetic field and the number of turns in the coil. |
| What are the SI units of magnetic field strength | Tesla |
| Only what shell x-rays of tungsten are useful for imaging | k-shell |
| Proton | A positively charged particle located inside the nucleus of an atom. It also defines the atomic number of an element. |
| Neutron | A particle located inside the nucleus of an atom that has no charge. |
| Electron | A small particle that usually orbits around the nucleus of an atom and has a negative charge |
| Atomic Number | The total number of protons an element has, which consequently defines what the chemical element is. |
| Ionization | The release of an electron by an orbiting shell |
| Radiation | The transfer of energy by the ionization of atoms |
| Photon | A packet of electromagnetic energy |
| Properties of a photon | Frequency, wavelength, amplitude and velocity |
| Compton Scattering | The source of most occupational radiation exposure. An outer shell electron is struck and ejected (compton electron). The x-ray continues in a different direction with less energy, and it produces fog. |
| Insulator | Any material that does not allow electron flow |
| Semiconductor | A material that under some conditions behaves as an insulator, and in other conditions, behaves as a conductor |
| Conductor | Any substance through which electrons flow easily |
| Resistance | Anything that hinders or opposes the electric current flow of charge particles |
| Formula to find the number of electrons in a shell | 2^n, where n = the number of the shell |
| What is the smallest particle that has all the properties of an element | Atom |
| What are the fundamental building blocks of matter | Atoms(Elements) and Molecules(Compounds) |
| What are the seven types of energy | Potential, Kinetic, Chemical, Electrical, Thermal, Nuclear and Electromagnetic |
| What is the smallest particle that has all the properties of a compound | Molecule |
| At what speed does all electromagnetic radiation travel | 3.0 x 10^8 |
| What two natures does electromagnetic energy behave in | Wave and Particle |
| How are frequency and wavelength related | Inversely proportional |
| What is the smallest unit of negative electric charge | Electron |
| If two negatively charged objects are brought near to each other will they be attracted or repelled | Repelled |
| If an object gains an electron does it become positively or negatively electrified(charged) | Negatively |
| Can protons move freely from one atom to another | No |
| What are the three ways electrification can be created | Induction, Friction and Contact |
| What are the 3 main factors that characterize a simple circuit and their unit of measurement | Voltage (Volts), Current (Amps) and Resistance (Ohms) |
| the voltmeter connects to what kind of circuit | Parallel |
| An ampmeter connects to what kind of circuit | Series |
| What type of circuit does voltage remain constant | parallel |
| What are the four factors that influence the resistance of a conductor | Cross sectional Area, Material Type, length and temperature |
| Define electrostatics. | Branch of physics dealing with stationary or resting electric charges. |
| Define electrification. | Insufficient or over abundance in the amount of electrons. |
| Define negative Electrification. | Excessive amount of electrons.( negative charge) |
| Define ground. | Wire Going straight into the earth to help dissipate electrical charges |
| What does an electroscope do? | It detects the presence and sign of an electric charge. |
| Define electrification by induction. | When an uncharged metallic object experiences a shift of electrons when brought into the electric field of a charged object. |
| What is the first law of electrostatics? | Like charges repel; unlike charges attract. |
| What is the second law of electrostatics? | force between 2 charged particles is directly proportional to the product of their strengths, and inversely proportional to the square of the distance between them |
| What is the third law of electrostatics? | Charges reside on the external surfaces of conductors. |
| What is the fourth law of electrostatics? | The concentration of charges on a curved surface of a conductor is greatest where curvature is greatest. |
| What is the fifth law of electrostatics? | Only negative charges can move in a solid conductor. |
| What is another name for static electricity? | Resting charges. |
| What particle moves when electrification occurs? | Only the electrons move. |
| What is the movement of electrons in insulators? | Electrons do not flow freely. |
| A charged body brought near an uncharged body is an example of what type of electrification? | Induction |
| Define electrodynamics. | The science of electric charges in motion. |
| Under what conditions does an electric current consists of a flow of charged particles | Gas, Ionic solution, Metallic conductor, Vacuum |
| What are the two sources of electric current | Cells/Batteries and Dynamo/Generator |
| Define potential difference. | Difference in electrical potential energy between 2 points in an electric circuit. |
| What is the UNIT of potential difference | Volt |
| Define volt. | Potential difference maintaining a current of ampere in a circuit whose resistance is 1 ohm. |
| Define electromotive force. | The maximum difference of potential between the terminals of a battery. |
| Define current. | Amount of electric charge flowing per second. |
| What is the UNIT of current | Ampere |
| What is an ampere | 1 coulomb quantity of electric charge flowing per second. |
| Define resistance. | Property of circuit opposing or hindering flow of electric current. |
| What is the UNIT of electrical resistance | OHM |
| Define OHM. | The resistance of a standard volume of mercury under standard conditions. |
| On what factors does the resistance of a conductor depend | Material, Length, Cross-sectional area, and Temperature |
| Define dry cell. | Used in flashlights, consists of carbon rod surrounded by manganese dioxide, immersed in ammonium chloride paste, zinc chloride, water. |
| Define wet cell. | Consists of hard rubber or plastic case containing sulfuric acid with immersed electrodes. |
| How does temperature affect metal conductors | The resistance becomes greater as the temperature rises. |
| Define OHM's law. | The value of the current in a metallic circuit equals the potential difference divided by the resistance. (I*R=V) |
| Define ammeter. | Meter that measures in amperes. (in series) |
| Define voltmeter. | Meter that measures, in volts, the potential difference between any two points in a circuit. (in parallel) |
| What is the unit of power | Watt |
| What is the equation for power loss | P = I^2*R watts |
| What is the formula that defines power loss in an electrical circuit | P = I^2*R |
| A gasoline engine will convert chemical energy to what type of energy | Mechanical energy |
| What type of charge moves in a conductor | Negative charges |
| What effect does a low temperature have on resistance | Decreases resistance |
| What effect does a high temperature have on resistance | Increases resistance |
| What is measured by a meter wired in series with a resistance | Current(Amperage) |
| Electric insulators inhibit movement of what | Electric charge |
| A closed loop through which charges can flow is a(n) _______ | Electric Circuit |
| The property that determines how much current will flow | Resistance |
| A flow of one coulomb per second | Ampere |
| Device that measures current | Ammeter |
| Devices designed to have specific resistance | Resistor |
| Device that measures potential difference | Voltmeter |
| What is the unit of electrical potential? | Volt |
| When an x-ray interacts with inner-shell electrons and is completely absorbed, it has undergone which interaction? | photoelectric |
| Atoms that have the same number of protons but a different number of neutrons are called ____________. | Isotopes |
| What is the bonding that occurs because of an electrostatic force (attraction of opposite charges) between ions? | ionic bond |
| What is the chemical union, between atoms, that is formed by sharing one or more pairs of electrons? | covalent bond |
| Any quantity of a molecule is a chemical _________. | compound |
| Atoms of various elements may combine to form what kind of structures? | molecules |
| Atoms that have the same atomic number but different atomic mass numbers are: | isotopes |
| In the neutral atom, the number of electrons is equal to the number of protons. What is the number of protons called? | atomic number, represented by "Z" |
| The number of protons plus the number of neutrons in the nucleus of an atom is called: | atomic mass number, symbolized by "A", never a whole number |
| What is centrifugal force? | the outward push or flying out from the center force so electrons maintain their distance from the nucleus while traveling in a circular or elliptical path |
| What is used to convert mechanical energy into electric energy? | a generator is used to convert mechanical energy to electrical energy |
| What is used to convert electrical energy into mechanical energy? | a motor by passing a coil or loop of wire through a magnetic field |
| What is electrical energy? | work that can be done when an electron moves through an electric potential difference (voltage) |
| What is electricity? | the flow of electrons |
| How do two atoms that are attracted to each other result in an ionic bond? | they have opposite electrostatic charges |
| Which shell has the highest binding energy? | K-shell |
| The more closer an electron is to the nucleus,and the greater the total number of electrons in an atom, the... | more tightly it is bound |
| The strength of attachment of an electron to the nucleus is referred to as what? | electron binding energy |
| What is the force that keeps an electron in orbit? | centripetal, the inward pull |
| What does the number of electrons in the outermost shell determine? | the valence of an atom |
| What is the number of electrons in the outermost shell of an atom(valence) equal to on the ptable? | it's group in the periodic table |
| What is the most electrons contained in the outer most shell of a stable atom | eight |
| What is the most electrons contained in the inner most shell | two |
| How many electron shells are there | seven |
| What is the first shell referred to as | K |
| What is the last shell referred to as | Q |
| What determines the chemical element | the number of protons |
| What are the particles in the nucleus called | nucleons |
| What are the two types of nucleons contained in the nucleus | protons and neutrons |
| What does the shell arrangement tell us about an atom | how it reacts chemically; how it combines with other atoms to form molecules |
| What do the shells represent | different electron binding energies or energy levels |
| The closer an electron is to the nucleus... | the greater its binding energy |
| What is the normal state of an atom | electrically neutral, charge is zero |
| What is ionization | the removal or addition of an orbital electron in an atom |
| If an atom has an extra electron or has had an electron removed, it is said to be what | ionized |
| The maximum number of electrons that can exist in each shell increases with what | the distance of the shell from the nucleus |
| What are the fundamental particles of an atom | electron, proton, neutron |
| What does the atom consist mainly of | empty space |
| What is an atom | the smallest particle of matter that has all the properties of an element |
| when characteristic x-rays are produced, the energy is characteristic of | the atomic number of the target |
| 8 Forms of Energy are | Mechanical, Thermal, Light, Electrical, Chemical, Atomic, Molecular, Nuclear |
| What is work | Force Times Distance |
| Who came up with the solar system theory of an atom | Bohr |
| A substance is a | definite combination |
| a neutral atom has what charge | no charge |
| A Conductor has what kind of valence | +1, +2 |
| A semiconductor | +/-3 and +/- 4 |
| Insulator | -2,-1 and 0 |
| A stable octet has what valence | 0 |
| Covalent Bonding | Sharing of Orbital electron |
| Ionic bonding is | an attraction between electrons but no sharing |
| The Horizontal rows of the P.table represent what | # of Shells and ranges from Non Metallic to Strong Metallic |
| Inertia is defined as what | A body at rest to stay at rest and a body in motion to stay in motion |
| Work is the expenditure of ____ to overcome inertia | energy |
| Energy is defined as | actual or potential ability to do work |
| Mechanical energy is subdivided into 2 groups, list them | Kinetic and potential |
| Kinetic energy is what | energy in motion |
| potential energy is what | energy at rest |
| Kinetic and potential energy are ____ related | inversely |
| E=MC^2 means what | All energy in the universe can not be created or destroyed and stays constant. |
| Power formula | force*distance ------------- time rate of doing work |
| A mixture is what | an impure form of matter |
| Substances are what | definite compositions or pure forms of matter |
| Elements are what | simple substances, when melted they do not change |
| Compounds/complex substances are what | elements that have combined together example. H2O |
| Molecule is what | smallest particle having all the properties of the compound *1 molecule of H2O* |
| Atoms are what | smallest particle having all the properties of the substance |
| What is the electron spin theory | Electrons Spin on an axis and orbit a nucleus |
| 1/12th of the mass of a carbon 12 nucleus is what | AMU-Atomic Mass Unit |
| Chemical properties of an element depend on its what | Valence |
| Ionization can occur one of these 6 reactions happen | 1.Exposure to Xrays or Gamma Rays 2.Exposure to a stream of electrons 3.Radionuclides decay 4.Exposure to light 5.Exposure to chemicals 6.Exposure to Thermionic emission |
| what is electrolysis | Chemical ionization |
| What is the charge of a Cation | Positive |
| What is the charge of a Anion | Negative |
| Electrons move from _____ to _____ in the tube | Cathode to Anode |
| A branch of physics that deals with stationary or resting electric charges | static electricity |
| If electrons are removed via friction what charge does that make the object | positive |
| What is the name of the zone that surrounds ever charged body. | Electric Field |
| When using electrification by induction when bringing a negatively charged object near an uncharged object what charge will the uncharged object take on at the end closest to the charged object | Positively |
| The earth is an infinite reservoir for what | electrons |
| Ground potential equals ____ | 0 |
| Laws of electrostatics 1-3 | 1.Likes repel, opposites attract 2.Force b/t 2 charges is Directly proportional to the product of their quantities and inversely proportional to the square of the distance b/t them 3.Electric charges reside only on the external surface |
| Laws of electrostatics 4-5 | 4.charges concentrate on the greatest curvature 5.Only Negative charges can move though solid conductors |
| Static discharge in a large scale is called what | lightning |
| The science of electric charges in motion | electrodynamics or current electricity |
| Electrons flow thought the _____ band oof a conductor | conduction |
| a bath over which the current flows is what | electric circuit |
| A device that "opens" and "closes" a circuit | switch |
| Factors in a simple steady direct current | 1.potential difference 2.current 3.resistance |
| the difference in electrical potential energy b/t 2 points on an electric circuit | potential difference |
| The potential difference b/t 2 points represents the amount of ____ expended in moving a unit charge from one point to the other | work |
| The maximum difference of potential between the terminals of a battery or generator | Electromotive force (EMF) |
| Unit of potential difference or emf is the | Volt |
| The amount of electric charge flowing per second is | current |
| Current is measured in | Ampere |
| property of a circuit which opposes or hinders the flow of electric current | Resistance |
| Resistance is measured in | Ohm's |
| the reciprocal of resistance, or the ability of a circuit to conduct a current is known as | conductance |
| Nonconducting materials are known as ____ or _____ | insulators or dielectrics |
| the value of the current in a metallic circuit equals the potential difference divided by the resistance is the definition of what | Ohm's Law |
| What are the 2 types of batteries | 1.Dry 2.Wet |
| In steady direct current the electrons flow in what | One direction |
| what are the 3 essential parts of a circuit | 1.Battery 2.Conductor 3.Resistance or load |
| The current in a circuit supplied by a battery has a definite direction or ______ | polarity |
| Galvanometers are what | devices used to measure potential difference (Volts) and/or Current (Amperage) |
| An electrical circuit whose component parts are arranged end-to-end so that the current passes consecutively though each part | Series |
| A circuit where the component parts are connected as branches of the main circuit so the current is divided among them | Parallel |
| In a Series Circuit the Volts ____, the Amperage _____, and the Resistance_____ | Add up Stays the same Adds up |
| In a Parallel circuit the Volts _____, the Amerage _____, and the Resistance _______ | Stay the same Adds up Add the reciprocal |
| An excessive amount of Amperage in a circuit may cause a ______ | Overload |
| 2 Devices made to stop a circuit from overloading | 1.Fuse 2.Breaker |
| A device that stores electrical energy. | Capacitor(Condenser) |
| A capacitor does not make electricity, but only stores it. True or false | True |
| Capacitors do not have a limit on how much electrical energy it can store. | False, Capacitors can only hold as much as it is design allows it to. |
| To find the power of a current you must use what equation | I*V=P(Watts) |
| What is the unit for "Power" | watts |
| The Power loss formula is | I*I*R=Power Loss in Heat/sec |
| Power Loss is ______ to the square of the current | Proportional |
| The ability to attract Iron, cobalt, and nickle is what | Magnetism |
| Any material that attracts iron, cobalt, and nickle | magnet |
| 3 types of magnets | 1.Lodestone--Natural 2.Alnico--Artificial 3.Electromagnet--Artificial |
| 3 Laws of magnetism | 1.Every magnet has 2 poles 2.Like poles repel, opposites attract 3.force is proportional to the product of the pole strength divided by the square of the distance b/t them |
| Natures of Magnetism | 1.breaking a magnet results in 2 magnets 2.Heating or hammering a piece of steel while it lies near a magnet causes the steel to magnetize 3.Stroking an iron bar with a magnet causes it to become magnetized |
| When dipoles all line up in the same direction it creates a what | domain |
| Non magnetized materials have their dipoles in what type of direction | random |
| if just as many dipoles are moving in one direction as the other the material is considered what | A non magnetic element |
| the summation of the fields of all the domains is what | magnetic field |
| the "lines" of a magnetic field are called what | Magnetic Flux |
| the less closely spaced the magnetic flux lines are the stronger the field will be. True or False | False. the Closer the lines the stronger |
| the strength of a magnetic field is proportional to the # of _____ per square centimeter | lines |
| Magnetic lines are directed from south pole to north pole of a magnet as curved lines in the surrounding space. True or False | False. the lines go from North to south on the outside of the magnet and South to North on the inside |
| Magnetic lines of force seem to repel each other when they are in the same direction. True or False | True. Likes repel and opposites attract |
| Magnetic fields are distorted by magnetic materials but are not affected by nonmagnetic materials. True or False | True. Diamagnetic materials are repelled by magnetic fields however, they do not influence them. |
| When a ferromagnetic material is brought near the north pole of a magnet the end farthest from the magnet will be what type of pole | North |
| The ease in which a material can be magnetized is what | magnetic permeability |
| The ability of a magnet to resist demagnetization is called what | Magnetic retentivity |
| Permeability and retentivity have a ______ relationship | Inverse |
| If a material has High permeability it has what retentivity | low |
| the 4 types of magnetic matter | 1.Ferromagnetic 2.Paramagnetic 3.Nonmagnetic 4.Diamagnetic |
| A _____ can detect magnetic lines of flux | Compass |
| The earths North pole is actually the South pole and the South pole is actually a North Pole, True or False | True |
| The Tesla is the SI unit for what | Magnetism |
| a branch of physics that deals with the relationship between electricity and magnetism | Electromagnetism |
| Who discovered that a magnetic compass needle turns when placed near copper wire carrying a direct current | Oersted |
| a ____ _____ always surrounds a conductor in which an electric current is flowing | magnetic field |
| The Left hand Thumb rule is.... | when the wire is grasped in the left hand with the thumb pointing in the direction of the electron current, then the fingers encircling the wire will indicate the direction of the magnetic lines around the current |
| A magnetic field exits around a wire only while a ______ _____ is flowing | electric current |
| a Helix is what | A coil of wire conductor |
| the north pole of a iron core of a electromagnet is always on the negative side of the current. True or False | True |
| A Solenoid is a ... | helix carrying an electric current |
| How do you create a electromagnet | Put an iron core in a solenoid |
| Adding an iron core (Increases or Decreases) the magnetic field in a electromagnet | increases |
| Michael Faraday discovered what | that moving the magnetic fields can induce electron flow in a conductor |
| Whenever a conductor cuts across magnetic flux, or is cut by magnetic flux, an electromotive force *EMF* or potential difference is induced in the conductor. This is called what | electromagnetic induction |
| An interaction between a single line of force and a single loop of conductor is called what | Flux Linkage |
| 4 Factors that determine the size or magnitude of an induced EMF | 1.Speed-more lines cut per second higher the EMF 2.Strength-the stronger the magnetic field the higher the induced EMF 3.Angle-The closer the angle is to 90degrees the stronger the EMF 4.Turns-the greater the number of turns the stronger the EMF |
| If a stationary wire was surrounded by a magnetic field of varying strength would an EMF be produced. | Yes |
| An EMF is induced in a conductor moving relative to a magnetic field even if the circuit is open because EMF represents the potential difference b/t the ends of the conductor. True or False | True, though no current will flow unless it is closed |
| 3 ways to induce EMF | 1.Moving wire and stationary magnetic flux 2.Moving magnetic Flux and stationary wire 3. stationary wire and magnetic flux varies in strength |
| the magnitude of the induced EMF is directly proportional to the number of lines per second crossing the conductor, True or False | true |
| To determine the relationships between the motion of the conductor, and the magnetic field and the direction of the current you need to use what | Left hand rule or Dynamo rule |
| If the motion of the conductor is going upward and the magnetic flux lines are perpendicular to the motion. then the current will flow in which direction left or right | right |
| when a secondary opposite flowing current occurs in a newly closed circuit because of the lines of flux are cutting across the coil. this is called what | Self-Induction |
| Self-Induction EMF _____ the applied EMF | opposes |
| When the switch is reopened after a time the secondary self-induced emf ____ with the applied emf until they both reach 0 | falls |
| In Alternating current the "rise" to the peak of the wave is where the self-induction takes place. True or False | True |
| Mutual Induction is what | Placing a pair of insulated wire coils side by side and applying an alternating current to one will induce an EMF in the other |
| a device that converts mechanical energy to electrical energy by electromagnetic induction is called a what | Electric Generator or Dynamo |
| A coil of wire that is rotated mechanically in the magnetic field is called a what | armature |
| 2 things needed to create a generator | 1.powerful electromagnet 2.armature |
| Slip rings are used how in a generator | they are used to transfer the current from the armature to the wire conductor |
| Do slip rings move in a generator? | No, the armature arms slide around the inside the ring. |
| What material are the "brushes" made up of in a generator. | Carbon |
| a current which periodically reverses its direction is called a what | Alternating current *AC* |
| The S shaped wave form of moving AC current is called what | Sine or Sinusoidal |
| A Cycle of AC current is what | the distance between 2 corresponding points on the curve, that represents a full rotation |
| # of Cycles per second is | 60 |
| # of Alternations per second | 120 |
| RMS stands for... | Root Mean Square |
| By what formula would find the EFFECTIVE Voltage on a AC circuit | Total V * .707 = Effective Voltage |
| By what formula would find the MAXIMUM Voltage on an AC circuit | Effective V * 1.41 = Maximum Voltage |
| RMS can be used for Voltage or Amperage. True or False | True |
| AC causes a fluctuation in the strength and direction of the magnetic field set up around a coil. True or False | True |
| Back EMF is what | Opposite the applied EMF, This is caused by the back bias of the sine wave |
| Inductive Reactance is what | the bucking effect of the back emf associated with the rapid self-induction that occurs during the entire time that an AC circuit is on |
| All resistive factors in a circuit is what | Impedance |
| small capacitors that hinder the flow of current in AC | capacitive reactance |
| an opposition which tries to change the amount of current flowing | Inductance, can be used interchangeably with Self Induction |
| In a DC circuit this device allows current to flow only until it has reached a full charge and then stops flowing. | capacitor |
| Ohm's Law for AC is what formula | Effective current=Effective Voltage/impedance or I=V/Z |
| The ring used in DC generators is called what | commutator or split ring |
| the split ring allows the AC current created by the Armature to only pass through as DC current. True or False | True |
| Commutator rings are attached directly onto the armature ends. True or False | True |
| A X YY chart with consecutive arches all above the X axis is called what | pulsating direct current |
| 2 Advantages of AC | 1.needed to operate transformers 2.can be transmitted over great distances |
| Power loss is not proportional to the square of the amperage. True or False | False, Power loss is proportional to the square of the amperage. P=I*I*R |
| Power loss is measured in what | Heat |
| a device that converts electrical energy to mechanical energy is called | electric motor |
| whenever a conductor carrying an electric current is placed in a magnetic field there is a force or side trust on the conductor. True or False | True |
| For an Electric motor to work 2 conditions must apply | 1. conductor must carry a current 2. must be located in a magnetic field |
| the conductor experiences a force that is directly proportional to its length or number of turns, the strength of the magnetic field, and the size of the current. True or False | True |
| The force is decreased when the conductor is in the form of a coil. True or False | False, The force is INCREASED |
| with the Right hand or Motor rule the direction of the Thumb represents ______, the index finger represents_______, and the Middle finger represents _______. | Thumb represents direction that the conductor will move, Index finger direction of the magnetic field and the middle finger represents direction of the electrons |
| AC motors have ______ Rings and DC motors have _____ rings | slip, commutator |
| Motors consume less current than a heating device why. | The back emf that is created in the motor acts as a generator sending current back to the main lines. |
| name the 2 types of electric motors | 1. Direct current motor 2. Alternating Current motor |
| Alternating current motors come in 2 varieties what are they | 1.Synchronous 2.Induction |
| Synchronous motors create Alternating current however it is built like a single phase ____ generator | AC |
| Synchronous motors must rotate at 1/2 the speed of its generator supplying the current. True or False | False, the motor must rotate at the same speed *rotations per min* as the generator supplying the current |
| A disadvantage of synchronous motor lies in the limited speed in which it operates. True or False | True |
| Induction motors use a _____ | stator |
| Even numbers of stationary electromagnets distributed around the periphery of a tube is called a what | stator |
| Stators are supplied by a ______ current to ensure proper spin of the iron core | multiphase |
| a device used to measure AC that will not freeze due to the rapid alternations in the current is called what | electrodynamometer |
| Electrodynamometer's measure what | Voltage or Current |
| An electromagnetic device which changes an AC current from low voltage to high voltage or from High to low, with out loss of appreciable amount of energy. | Transformer |
| Acceptable amount of energy loss in a transformer is less then ____ percent | 5 |
| Transformers transfer electrical energy from one circuit to another without the use of moving parts or any electrical contact between the 2 circuits. True or False | True, it is done by elecromagnetic mutual induction |
| 4 types of transformers | 1.Air Core 2.Open Core 3.Closed Core 4.Shell-type |
| The primary coils is the side that is connected to the _____ of power | source |
| The secondary coils receive energy from the primary coils though induced EMF. True or False | True |
| Primary Coils are considered the ____ side | input |
| Secondary Coils are considered the _____ Side | output |
| An important principle of electromagnetic induction is the EMF induced in any coil is directly proportional to the number of turns in the coil that cuts, is cut by, or links with, a given magnetic flux. True or False | True |
| If the primary coil of a transformer has one loop and the secondary coil has 2 loops this would be considered a _____ _____ transformer | step up |
| the EMF induced in the secondary coil is to the emf in the primary coil, as the number of turns in the secondary coil is to the number of turns in the primary coil represents what | Transformer law |
| Transformer Law simply stated as a formula is what | Vs Ns -- = -- Vp Np Vs=Voltage Secondary coil Vp=Voltage Primary Coil Ns=# of Turns Secondary Coil Np=# of Turns Primary Coil |
| Step up transformers increase or decrease the output voltage | increase |
| a step down transformer has more loops on the secondary coil then on the primary. True or False | False a step down transformer has fewer loops on the secondary side then primary |
| When measuring the current in a transformer what formula must be used | Is Vp -- = -- Ip Vs Where Is=Current in Amps in secondary Ip=Current in Amps in Primary Vs=Voltage in secondary Vp=Voltage in primary |
| Current and Voltage are _____ proportional in transformers | inversely |
| a step up transformer increases ____ but decreases _____ | voltage, amperage |
| power output of an xray transformer is rated in ____ | KVA *kilovolt-amperes or killowatts* |
| to find the KVA of a xray generator you need to use what formula | Kvp * Amperage = KVA be sure to change mA to A |
| A transformer that consists of 2 insulated coils lying side by side is called | Air Core Transformer |
| A transformer that consists of 2 insulated coils with iron cores lying side by side is called | Open Core Transformer |
| Air core transformers still have alot of power loss due to loss of magnetic flux at the ends of the cores this is called what | leakage flux |
| heavily insulated coils wound around a square or circular laminated iron ring/core, immersed in a container full of oil is called a what | Closed Core Transformer |
| Closed core provides a continuous path for the magnetic flux so only a small fraction of magnetic energy is lost to leakage. true or false | True |
| Windings are also known as | coils around a closed core transformer |
| The oil in a closed core transformer has ____ ____ created because of the magnetic flux | eddy currents |
| The oil is used as a _____ for the coils, reducing the amount of heat loss | coolant or insulation |
| Laminated core, consisting of a pile of sheets of silicon steel each having 2 rectangular holes with the primary and the secondary coils both wound around the central section of the core is called what | Shell Type Transformer |
| Shell type transformers are submerged in what to increase insulation | oil |
| A common type of lamination used on transformer cores is what | Silicon |
| A galvanometer with low resistance in a parallel is capable of measuring current when connected in series in a DC circuit. This device is a Ammeter True or False | True |
| A galvanometer protected by a high resistance in series measures potential difference when connected in a parallel. This is known as a voltmeter. True or False | True |
| 3 Types of Power Loss in Transformers | 1.Copper losses 2.Eddy Current losses 3.Hysteresis Losses |
| Loss of power due to the lack of cross-section on a copper conductor is called what | Copper Losses |
| Power loss due to a large swirling current created by electromagnetic induction. | Eddy Current |
| power loss due to the magnetic domains in the core are constantly rearranging themselves is called | hysteresis |
| A device that varies input voltage to a transformer to control its output voltage | Autotransformer |
| A autotransformer is connected between the secondary side of the high voltage transformer and the xray tube. True or False | False, Located between the power source and the primary side of the transformer |
| Another name for Autotransformer | variable transformer or KVP selector |
| Autotransformers are _____ wire coil wound around a _____ core. | Single, Single |
| Autotransformers work on the principle of ____ induction | Self |
| Autotransformer law | Vs #T1 -- = --- Vp #Tt Vs=Voltage secondary Vp=Voltage primary #T1=# of tapped turns #Tt=# of Total turns |
| Why is it not recommended to change KVP while the exposure is happening | To prevent sparking that may occur causing damage to the equipment |
| 3 ways of controlling the filament current are | 1.Choke Coil 2.Rheostat 3.High Frequency circuit |
| Choke coil work on the principle of mutual induction. True or False | False. they work on the principle of Self Induction |
| Choke Coils require a _____ current | Alternating |
| As more back EMF is applied to a choke coil the Resultant(left over current) is reduced. True or False | True |
| A variable resistor is also known as a | Rheostat |
| Rheostats can use either DC or AC. True or False | True |
| With H-F generators is became possible to obtain a nearly constant voltage output with ripple of less than 2 percent. True or false | True |
| High Frequency Generators turn AC current into DC, then change it back to AC, then again back to DC for the xray equipment to work. True or False | True, AC comes in and is rectified to DC current, flows into the Capacitor, then into the H-F Converter to be changed into AC, it is then used in the Transformers, then changed back to DC in the Filter/Capacitor to be used in the Tube. |
| ____ is defined as the process of changing AC to DC | Rectification |
| 2 main systems of rectification are | 1.Self-rectification 2.Vacuum tube or solid state diode rectification |
| Vacuum Tube diodes are also called ____ _____ | valve tubes |
| All rectifying systems are connected between the primary side of the xray transformer and the xray tube. True or False | False, between the SECONDARY side of the transformer and the tube |
| Primary disadvantage of Self rectification is | limitations to low exposure factors |
| Self rectification is also known as | self half wave |
| Diode rectification allows current to only pass in one direction only. True or False | True |
| if only one or two diodes are present in a circuit it is considered ____ ____ rectification | Half Wave |
| If there are 4 diodes in a circuit it is considered _____ _____ rectification | Full Wave |
| Rectifiers suppess the inverse voltage reducing the possibility of reverse flow this allows greater use of higher technical factors. True or False | True, protects the anode from becoming hot enough to produce an electron cloud that would allow the electrons to jump back at the cathode. |
| Disadvantage in using 4 diode rectification is what | using the entire AC wave results in the production of a high percentage of low energy xrays but can be eliminated by either filtration or 3phase/high frequency generator |
| Full wave rectification allows for a higher tube rating or heat-loading capacity compared to a half/self rectification. True or False | True |
| Solid State diode rectifiers are used as _______ | semiconductors |
| 3 types of energy bands | 1.Valance-where the electrons live normally 2.Forbidden-no electron can stay here 3.Conduction-allows for the movement of the electrons |
| In a conductor the Valance band and the conduction band have a large forbidden band. True or False | False, in a conductor the 2 bands overlap allowing for electrons to move freely |
| In an insulator the valance band and the conduction band overlap with no forbidden band. True or False | False, in an insulator the forbidden band is very large, so no electrons can "jump" to the conduction band |
| in a semiconductor the valance band and the conduction band have a small forbidden band in between them. Allowing for movement under controlled conditions. True or False | True |
| ______ is the semiconductor we are familiar with in rectifiers | Silicon |
| What element is mixed in silicon to create a N-Type silicon compound | Arsenic |
| When Arsenic is mixed in silicon it is known as ______ | Doped |
| in N type silicon the n stands for what | negative |
| Arsenic gives silicon extra what | electrons |
| what is the element that is mixed in silicon to create a P-Type silicon compound | Gallium |
| In P type silicon the P stands for what | Positive |
| Gallium gives silicon what | a deficiency of electrons creating a "Hole" |
| When combined together N-Type silicon and P-Type Silicon are attracted to each other. True or False | True |
| what is the name of the junction in a solid state rectifier | N-P Junction |
| When the electrons from the N-Type silicon drift towards the P-Type "holes" and they meet in the middle what happens. | The outside edges polarity flips and the electrons and holes are attracted back to the edges. |
| What is Barrier voltage or Potential hill | the potential difference between the positive and negative silicon ions in a solid state diode |
| Stacks of individual diodes are called what | modules |
| Advantages of the silicon rectifier over a valve tube are what (5) | 1.Compact Size 2.No Filament 3.Low Forward voltage drop 4.Low reverse current at max voltage 5.Long life due to rugged construction |
| If a rectifier has failed or is open then it causes the milliammeter to register only 1/2 the selected value causing radiographs to be consistently underexposed. True or false | True |
| When a rectifier blows it makes a loud squealing noise. True or False | False, It however does make a loud BANG sound |
| What is the test that can determine if a single phase unit has a damaged rectifier | Spinning top test |
| A _______ is used with 3 phase 12 pulse equipment to determine if a rectifier is damaged | oscilloscope |
| If trying to determine the # of dots that would be present in a half wave rectifier you would use what formula. | time * 60 = #of Dots |
| If trying to determine the # of dots that would be present in a full wave rectifier you would use what formula. | time * 120 = #of Dots |
| If given the # of dots in a half wave rectifier and you need to find out the time used to achieve it what formula would you use | # of dots / 60 = time |
| If given the # of dots in a full wave rectifier and you need to find the time used to achieve it, what formula would you use | # of dots / 120 = time |
| Electrical and magnetic components of an electromagnetic wave oscillate(vibrate) in mutually perpendicular planes. True or False | True (Selman 109 Fig 12.1) |
| 2 types of radiation that is produced during exposure name them. | 1.Bremsstrahlung 2.Characteristic |
| Brems radiation occurs when electrons slow down or decelerate near the nucleus of an atom. True or False | True. |
| What are the different types of interactions that cause Brems radiation (3) | 1.Electrons come near the nucleus and are completely adsorbed releasing high energy photon 2.Electron makes almost complete circle around nucleus losing most of its energy creating midlevel photon 3.Electron skims the nucleus causing a low energy photon |
| Characteristic Radiation is created when an inner orbital electron is ejected and a outer shell electron drops into its place | True |
| Characteristic radiation is produced at tube potentials less then ____ Kvp | 69 |
| What is a pole transformer | transformer outside the building on electrical pole |
| Pole Transformers are a step down transformer True or false | True reduces the voltage to 120-240 for use with equipment |
| 120v-240v coming into the building is called what | Line Voltage |
| a 3 wire system that is coming into a building consists of what. | 2 hot wires (current flowing) and 1 ground |
| The part of the circuit connected to the primary coil of the transformer is the primary or low voltage circuit. True or False | True |
| The part of the circuit attached to the secondary coil of the transformer is the secondary or high voltage circuit. True or False | True |
| Portion of the circuit that is connected between the electrical source and the primary coil of the transformer is called what. | Primary Circuit |
| The Main switch is usually this | Double bladed, single throw switch |
| an AC voltmeter connected in parallel with the autotransformer, that is, across the primary circuit between the autotransformer and the transformer. this is called what | prereading kilovoltmeter |
| Remote control switch | Also known as exposure button |
| a timer using a wound spring with the accuracy of about 0.25 seconds. | Mechanical |
| _____ are used in 6pulse and 12pulse equipment with electronic timers | Thyristor |
| A Thyristor is what | A solid state device that functions like a thyratron but can provide much shorter and more accurate exposures |
| Thyratron is what | a special gas-filled triode that becomes conductive at a particular, critical voltage |
| Electronic timers are accurate down to ______ time | 1 millisecond |
| AEC stands for | Automatic Exposure Control |
| AEC uses 2 types of systems what are they | 1.phototube(photomultiplier) 2.Ionization chamber |
| The back up timer on AEC is used for what. | To shut off exposure in case of malfunction that causes the exposure to continue even after adequate image is acquired |
| The primary circuit of the Filament circuit supplies the heating current, but the current must be reduced to __-__ amps and __-__ volts by the rheostat | 3-5 amps 6-12 volts |
| Rheostats function using ____ law | Ohms |
| When Amperage goes up _____ goes down | Voltage |
| Filament transformers are ____ ____ transformers | step down |
| Filament transformers must be immersed in oil to provide sufficient insulation between the high voltage primary coil and the low voltage secondary coil. True or False | True |
| In modern xray units a ____ ____ _____ automatically adjusts the filament current to maintain constant ma over a wide range of Kv | Space Charge Compensator |
| The secondary coil of the transformer and all devices to which it is connected electrically are part of the ____ circuit | secondary |
| to measure the mA in the xray tube a _____ is connected in series in the high voltage circuit | milliammeter |
| Milliammeters are grounded together with the midpoint of the secondary coil of the transformer it is at zero potential and can be safely mounted to the control panel. True or False | True |
| Tube current is measured in milliamperes by the ______ in the high voltage circuit, while the filament current is measured by the _____ in the low voltage filament circuit | milliammeter, ammeter |
| mAs Meter (milliampere-second meter)measures the product of the mA and time. True or False | True |
| the ______ does not register until the xray switch is closed (type of meter) | milliammeter |
| when the main switch is closed but the exposure switch is open the _____ ______ and _______ should normally be activated (types of meters) | filament ammeter and kilovoltmeter |
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Ravann
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