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69 Cards in this Set

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Primary Funciton of Xray imaging system is to ..
convert electrical energy into electromagnetic energy (conversion of electric current into xrays)
Smallest unit of Positive Charge
Protons
Smallest unit of negative charge
Electrons
Electrons are free to move between
Orbits and Atoms
Electricity concerns the distribution and movement of ...
electrons
Electricity (electric charge) comes in units that are
either positive or negative in charge
Free to move from one atom to another.
Electrons
Fixed in the nucleus and cannot move around.
Protons
The study of stationary electric charges
Electrostatics
Charges at rest
Electrostatics
Laws of Electrostatics
Repulsion-Attraction
Inverse Square Law
Distribution
Concentration
Movement
Unlike Charges
Attract
Like Charges
Repel
Force between two charges is directly proportional to the product of their magnitudes and inversely proportional to the square of the distance between them
COULOMB LAW (inverse square law)
Charges reside on external surface of conductors (an attempt to repel from each other)
Distribution
Electric charge DISTRIBUTION is ... throughout or on the surface of conductors
UNIFORM
The greatest CONCENTRATION of charges will gather at the ....
sharpest area of curvature
Only .... charges move along solid conductors
Negative
Adding or removing electrons
Electrification
Electrification created by
Friction,
Contact,
Induction
Occurs when one object is rubbed on another (rub feet on wool rug) (Combining hair during winter)
Friction
Occurs when two objects touch (permits electrons to move from one object to another
Contact
Electrification by contact
Static Discharge
Resevoir for straty electric charges .. electric ground
Earth
unit of electric charge
Coulomb (1C = 6.3x10)
When an electric potential is applied to a copper wire, electrons move along the wire creating an electric current or ....
Electricity
Quantity of electrons flowing
Current (I)
Force with which electrons travel
Potential Difference (V) Voltage
Opposition to currtent flow
Impedance or Resistance (R)
Direction of electron travel
AC / DC
Electrons move from areas of .. concentration to .... concentration
High to Low
Current flow requires an ... of charge between two points
IMBALANCE
Flow of electrons through a conductor or semiconductor is known as
CURRENT
A current is produced whenever charges are ...
in motion (electrons are moving)
Quantity of electrons flowing
Ampere
1 ampere (A)=
1 coulomb/second)
Electric charges have ... energy to do work
Potential (stored energy)
Force that drives the electrons
Electrical Potential
Unit of Electrical Potential
Volt
Electrical Potential is called the
Voltage
The higher the ... the greater the ... to do work
Voltage, Potential
Electromotive Force (EMF)
the force or strength of electron flow; also known as potential difference (V)
EMF used to do work
Voltage
Residential voltage is
110 V
Xray imaging systems require how much voltage?
220 V
The unit of potential difference EMF (V)
Joule/Coulomb (J/C)
Difference in charge between 2 points required to make charges (electrons) move.
Voltage

(Greater voltages make charges (electrons) move faster.
Opposition to the flow of current through a conducting path
Electrical Resistance
All materials have varying degress of resistance, depending on ...
strength of electrical bonds
Resistance is measured in
Ohms
The symbol for Ohms
R
Eletrical resistance is dependent on what 4 things?
Materials conductivity
Length
Diameter
Temperature
Any substance through which electrons flow easily.
Touching results in shoch
Conductors
Any material that dose not allow electron flow
Touching does not result in shock
Insulators
Copper
Aluminum
Water
Conductors
Rubber
Glass
Porcelain
Insulators
Material that under some circumstances behaves as an insulator and in other conditions behaves as a conductor
Semiconductors
Silicon
Germanium
Semiconductors
Dependent on configuartion of atom's valence band, conduction band
Materials Conductivity
How is length related to resistance?
Directly related
How is diameter related to resistance?
Inversely related
How is temperature related to resistance?
Directly related; Increased atomic motion due to increased temperatrue prevents electrons from flowing freely.
Under normal conditions, to have a current flow theough a circuit path there must be:
a voltage and a complete path
The voltage across the total circuit or any portion of the circuit is equal to the current times the resistanct
Ohm's Law
V = IR
V = Voltage (volts)
I = Current (amps)
R = Resistance (ohms)
Ohm's Law
V = IR
I = V/R
R = V/I
Ohm's Law
Measured in Watts
Electric Power
Xray imaging systems require ... of electric power
20 - 150 kw
... determines how much work a circuit can do
Watts
P = IV
P = I(squared)R
Power formula based on Ohm's Law