Electrostatics and Electrodynamics Flashcards
the primary function of x-ray imaging system
to convert electric energy into electromagnetic energy
study of stationary electric charges
Electrostatics
T/F Matter has mass and energy equivalence
True
T/F Matter also may have electric charge
Ttrue
positive or negative
has potential energy
Electric Charge
smallest units
proton and electron
fundamental unit of electric charge
C (Coulomb)
1 C : […electron charges]
6.3x10¹⁸
an object that has too few or too many electrons
Electrified
the process of adding or removing electrons from an object
Electrification
Electrification is created by [..]
contact, friction, induction
process of making ferromagnetic material
magnetic
[process of generating current in a conductor by placing it in a changing magnetic field]
Electrification by Induction
a phenomenon whereby surfaces become electrically charged by touching
Electrification by Contact
charging process results in a transfer of electrons between the two objects that are rubbed together
Electrification by Friction
the object that behaves as a reservoir for stray electric charges
Electric Ground
EXPLAIN Electrostatic Laws
Unlike charges attract
Like charges repel
Electric field radiates OUT from POSITIVE charge
Electric field radiates TOWARD a NEGATIVE charge
Uncharged particles DO NOT have electric field
the lines of force exerted on charged ions in the tissues by the electrodes
it causes charged particles to move from one pole to another
+ = OUT
- = TOWARD
Electric Field
Laws of electrostatics
- unlike charges attract; like charges repel
- Coulomb’s law
- electric- charge distribution
- electric-charge concentration
-charges uniformly distributed in -surface
- sharpest curvature of surface
EXPLAIN Coulomb’s Law
electrostatic force is directly proportional to the product of the charges
inversely proportional to the square of the distance between them
Coulomb’s Law formula
F = k(QₐQb/d²)
F - electrostatic force
k - constant of proportionality [8.99 x 10⁹ N m²/c²]
QₐQb - charges
d - distance (m²)
k [constant of proportionality]
8.99 x 10⁹ N m²/c²]
T/F Electric charge distribution is uniform through or on the surface
True
SI Unit: Volt (V)
1V:1J/C or 1 potential energy/unit charge
Electric Potential
Study of electric charges in motion
Electrodynamics
People who work with electric current
Electrical engineer
 people concerned with current flow
Physicist
The four states of electric matter
Conductor, Insulator, semiconductor, superconductor
Any substance through which electrons flow easily
Conductor
Characteristics of a conductor
Variable resistance
Obeys Ohm’s law
Requires voltage
Examples of a conductor
Copper (Z = 29), aluminum (Z = 13) & water
Any materials that does not allow electrons flow
Insulator
Characteristics of insulator
Does not permit electrons
flow extremely high resistance
necessary with high voltage
Examples of an insulator
Glass, rubber, and clay
Any material that storm conditions behave as an insulator and as a conductor
Semiconductor
Characteristics of a semiconductor
Can be conductive
can be resistive
basis for computers
Examples of semiconductors 
Silicon (Si-14) and Germainium (Ge-32)
material that allows electrons to flow without resistance
Superconductor
Characteristics of a  Superconductor
No resistance to electron flow
no electric potential required
must be very cold
Examples of a Superconductor
Niobium (Nb-41) and titanium (Ti-22)
Demonstrated semi conduction [person, year]
William Shockley 1946
The property of some matter to exhibit no resistance below a critical temperature
Superconductivity 1911
The path of electron flow from the generating source through the various components and back again
Electric Circuits
T/F Increasing electric resistance results in a reduced electric current
True
The flow of electrons through a conductor
Direction is always opposite to the electron flow
Electric current/electricity
Electric current/electricity is measured in […]
Amperes (A)
1 A: 1C/s or 1 Electric charge/second
It is measured in volts (V)
1V: 1 J/c or 1 potential energy/unit charge
Electric Potential
measured in Ohms
Electric resistance
The voltage across the total circuit or any position of the circuit is equal to the current times the resistance
V=IR
Ohms law
Ohm’s Law formula
V=IR
R=V/I
I=V/R
Two basic types of electric circuits
Series circuit and parallel circuits
one circuit elements are connected in a line along the same conductor
Series circuit
Rules for a series circuit
- The same current flows through each part of a series circuit. It= I1 = I2 = I3
- The total resistance of a series circuit is equal to the sum of individual resistances. Rt=R1+ R2 + R3
- Voltage applied to a series circuit is equal to the sum of the individual voltage Vt= V1 + V2 + V3
Elements are connected at their ends 
Parallel circuits
Rules for parallel circuits
The total parallel circuit current is the sum of the individual branch currents It= I1 + I2 +I3
The voltage across each component in a parallel circuit is the same. Vt= V1=V2 =V3
The reciprocal of the total resistance is equal to the sum of the reciprocals of the individual resistances. 1/Rt= 1/R1 + 1/R2 + 1/R3
Inhibits flow of electrons
Resistor 
Provides electric potential
Battery
Momentarily stores electric charge
Capacitor
Measures electrical voltage
Ammeter 
Measures electric potential
Voltmeter
Turn circuit on and off by providing infinite resistance
Switch
Increases and decreases voltage by fixed amount (AC only)
Transformer
Variable resistor
Rheostat
Allows electrons to flow only in one direction
Diode
Electrons that flow in only one direction
Direct current
Electrons that flow alternatively in opposite direction (60-Hz)
Alternating current
Graphic representation of a wave
x-axis:time
y-axis: amplitude of electric current 
AC: sinusoidal
DC: straight line
Waveform 
measured in Watts (W)
1 W: 1A x 1V
Electric Power
Electric Power formula
P=IV
P=I^2R
T/F Electric charge of a conductor is concentrated along the sharpest curvature on the surface
True