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69 Cards in this Set
- Front
- Back
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Primary Funciton of Xray imaging system is to ..
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convert electrical energy into electromagnetic energy (conversion of electric current into xrays)
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Smallest unit of Positive Charge
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Protons
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Smallest unit of negative charge
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Electrons
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Electrons are free to move between
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Orbits and Atoms
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Electricity concerns the distribution and movement of ...
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electrons
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Electricity (electric charge) comes in units that are
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either positive or negative in charge
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Free to move from one atom to another.
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Electrons
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Fixed in the nucleus and cannot move around.
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Protons
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The study of stationary electric charges
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Electrostatics
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Charges at rest
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Electrostatics
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Laws of Electrostatics
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Repulsion-Attraction
Inverse Square Law Distribution Concentration Movement |
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Unlike Charges
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Attract
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Like Charges
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Repel
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Force between two charges is directly proportional to the product of their magnitudes and inversely proportional to the square of the distance between them
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COULOMB LAW (inverse square law)
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Charges reside on external surface of conductors (an attempt to repel from each other)
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Distribution
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Electric charge DISTRIBUTION is ... throughout or on the surface of conductors
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UNIFORM
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The greatest CONCENTRATION of charges will gather at the ....
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sharpest area of curvature
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Only .... charges move along solid conductors
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Negative
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Adding or removing electrons
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Electrification
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Electrification created by
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Friction,
Contact, Induction |
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Occurs when one object is rubbed on another (rub feet on wool rug) (Combining hair during winter)
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Friction
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Occurs when two objects touch (permits electrons to move from one object to another
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Contact
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Electrification by contact
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Static Discharge
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Resevoir for straty electric charges .. electric ground
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Earth
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unit of electric charge
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Coulomb (1C = 6.3x10)
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When an electric potential is applied to a copper wire, electrons move along the wire creating an electric current or ....
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Electricity
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Quantity of electrons flowing
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Current (I)
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Force with which electrons travel
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Potential Difference (V) Voltage
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Opposition to currtent flow
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Impedance or Resistance (R)
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Direction of electron travel
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AC / DC
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Electrons move from areas of .. concentration to .... concentration
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High to Low
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Current flow requires an ... of charge between two points
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IMBALANCE
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Flow of electrons through a conductor or semiconductor is known as
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CURRENT
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A current is produced whenever charges are ...
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in motion (electrons are moving)
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Quantity of electrons flowing
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Ampere
1 ampere (A)= 1 coulomb/second) |
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Electric charges have ... energy to do work
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Potential (stored energy)
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Force that drives the electrons
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Electrical Potential
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Unit of Electrical Potential
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Volt
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Electrical Potential is called the
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Voltage
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The higher the ... the greater the ... to do work
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Voltage, Potential
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Electromotive Force (EMF)
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the force or strength of electron flow; also known as potential difference (V)
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EMF used to do work
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Voltage
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Residential voltage is
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110 V
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Xray imaging systems require how much voltage?
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220 V
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The unit of potential difference EMF (V)
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Joule/Coulomb (J/C)
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Difference in charge between 2 points required to make charges (electrons) move.
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Voltage
(Greater voltages make charges (electrons) move faster. |
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Opposition to the flow of current through a conducting path
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Electrical Resistance
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All materials have varying degress of resistance, depending on ...
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strength of electrical bonds
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Resistance is measured in
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Ohms
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The symbol for Ohms
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R
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Eletrical resistance is dependent on what 4 things?
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Materials conductivity
Length Diameter Temperature |
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Any substance through which electrons flow easily.
Touching results in shoch |
Conductors
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Any material that dose not allow electron flow
Touching does not result in shock |
Insulators
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Copper
Aluminum Water |
Conductors
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Rubber
Glass Porcelain |
Insulators
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Material that under some circumstances behaves as an insulator and in other conditions behaves as a conductor
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Semiconductors
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Silicon
Germanium |
Semiconductors
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Dependent on configuartion of atom's valence band, conduction band
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Materials Conductivity
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How is length related to resistance?
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Directly related
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How is diameter related to resistance?
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Inversely related
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How is temperature related to resistance?
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Directly related; Increased atomic motion due to increased temperatrue prevents electrons from flowing freely.
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Under normal conditions, to have a current flow theough a circuit path there must be:
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a voltage and a complete path
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The voltage across the total circuit or any portion of the circuit is equal to the current times the resistanct
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Ohm's Law
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V = IR
V = Voltage (volts) I = Current (amps) R = Resistance (ohms) |
Ohm's Law
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V = IR
I = V/R R = V/I |
Ohm's Law
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Measured in Watts
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Electric Power
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Xray imaging systems require ... of electric power
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20 - 150 kw
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... determines how much work a circuit can do
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Watts
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P = IV
P = I(squared)R |
Power formula based on Ohm's Law
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