1 Flashcards
is a form of energy resulting from the existence of charged particles (such as electrons or protons), either statically as an accumulation of charge or
dynamically as a current
electricity
a secondary energy source that can be generated
from primary sources such as fossil fuels, nuclear, and renewable resources like
sunlight, wind, and hydropower.
electricity
the flow of electric charge
electricity
The
unit of measure for electric charge is
coulomb
the unit of measure for the flow of
electric charge is measured in
amperes
the force that drives the electric charge
voltage
voltage is measured in
volts
opposes the flow of the electric current
resistance
resistance is measured in
ohms
2 types of electricity
static and dynamic electricity
the result of an imbalance between negative
and positive charges in an object. These charges can build up on the surface of an object until they find a way to be released or discharged.
static electricity
the flow of electric charges through a
conductor; in other words, an electric current.
dynamic electricity
Electrification of objects occurs when they gain a
net positive charge
or a net negative charge
An object may be electrified in _ ways:
3
When two objects are rubbed together, electrons may transfer from one object to the other.
The object that gains electrons becomes negatively charged, while the object that loses electrons
becomes positively charged.
friction
friction: the object that gains electrons becomes _____, while the object that loses electrons
becomes ______.
negatively charged, positively charged
When a charged object comes into direct contact with a neutral object, electrons transfer between them. This results in the neutral object acquiring the same type of charge as the charged object.
Conduction
In this method, a charged object is brought near a neutral object without touching it. This causes a redistribution of charges within the neutral object, creating regions of opposite charges.
induction
study of stationary or resting electric charges
electrostatics
the attractive or repulsive force between two electrically charged objects
electrostatic force
the electrostatic force between two charges is directly proportional to the product of their quantities and inversely proportional to the square of the distance between them
coulomb’s law
the steady flow of electric charges or the flow of electrons from atom to atom
dynamic electricity
more commonly known as the electric current or electricity
dynamic electricity
electrons in the more remote orbitals experience ______ from the nucleus and are also repelled by other electrons, more loosely bound.
less force of attraction
2 outer bands
valence, conduction band
material with a large number of electrons in the conduction band =
good electrical conductor
materials that readily allow a flow of electrons.
conductors
5 electrical conductors
silver, gold, copper, steel, sea water
conductor -
overlap
materials with no electrons in the conduction band =
good electrical insulator
will only allow electron flow in extreme conditions
insulators
insulator-
large gap
5 electrical insulators
rubber, glass, oil, diamond, dry wood
behaves as an insulator and a conductor
semi-conductors
silicon and germanium are examples of this
semi-conductors
semi-conductor-
small gap
the movement of electric charge or is the moving electrons
electric current
rate of flow of electrons
electric current
the number of electrons passing through a given point per unit time
electric current
1 ampere=
1 coulomb flowing at a given point in 1 sec
2 types of current
direct current DC AND alternating current AC
type of current that flows in only one direction
DC
battery is a good example of this type of current
DC
current that changes direction in cycles as the electric potential of the source changes
AC
an example of this type of current is electric socket
AC
2 current through an xray tube
filament current, tube current
small current applied to the filament of the xray tube
filament current
rate of flow of electrons that have travelled across the tube
tube current
filament current of about 5-7 A will generate tube current measured in
milliamperes mA
driving force which moves the electrons along the conductor
electric potential
the ability to do work because of separation of charges
electric potential
electrons flow from abundance to deficiency and will continue to do so as long as that difference exists
electric potential
unit of electric potential
Volt V
this is what propels the electrons to move from cathode to anode even in the absence of conductor
electric potential
the impedance to the flow of electrons, reduces the flow of electric current through a circuit. also dependent on the material used as a conductor.
electric resistance
measure of how the device or material reduces the electric current flowing through a circuit
electric resistance
factors affecting resistance
material, length, cross-sectional area, temperature
long conductor has more resistance
small cross-sectional area has more resistance
metallic conductors, as temp rises, resistance is also greater
relationship between voltage, current, resistance
Ohm’s law
only applies to metallic conductors
ohms’ law
voltage across the total circuit or any part of that circuit is equal to the current multiplied by the resistance
ohms law
law stating that current is proportional to voltage and inversely proportional to resistance
ohms law
power loss: lost energy in the cable is converted to
heat
power loss can be kept to minimum by
reducing current flowing within the cable, reducing resistance of the cable
usual incoming line voltage for xray machine in the philippines
220 V, 60 hz
AC
single-phase/three-phase power
Xray machine can be divided into
control console, high voltage generator, xray tube
allows the radiologic technologists to control the xray tube current and voltage. most familiar to the radtechs
control console
increases the low voltage from autotransformer to high voltage in kilovolts
high-voltage generator
converts ac to dc and provides the current necessary for the filament
high-voltage generator
primary part of the xray imaging system
xray tube
converts electrical energy into electromagnetic energy in the form of xray
xray tube
