Midterms | Unit 2.1 Electricity Flashcards
Electricity and Magnetism are manifestations of a single underlying —
electromagnetic force
Converts electric energy into electromagnetic energy
X-ray Imaging System
X-ray Imaging System’s primary function
Converts electric energy into electromagnetic energy
Differentiate Electrostatics and Electrodynamics
Electrostatics is the study of stationary electric charges.
Electrodynamics is the study of electric charges in motion
The study of the distribution of fixed charges
Electrostatics
Types of electric chrages
Electric Potential (V)
Electric Current (I)
Electric Potential is measured in —
Volt
Electric current is measured in —
Ampere
Potential energy per unit charge
Volt
One Coulomb of electric charge
flowing per second
Ampere
Relation of Volt to electric charge
Volt is potential energy per unit charge (1 V = 1 J/C)
Relation of Ampere to electric charge
Ampere is one Coulomb of electric charge flowing per second (1 A = 1 C/s)
Smallest units of electricity
Electron and proton
Fundamental unit (S.I)
Coulomb
1 C= ?
10^18 electron chrages
Transfer or movement of an electron from one object to another object.
Electrification
Electrification can be created in what ways?
Friction
Contact
Induction
When one object is rubbed against another
Friction
When two object touch, permitting electrons to move from one to the other
Contact
The process of electrical fields acting on another without contact
Induction
Most important method (used in the operation of electronic devices)
Induction
If object has too few or too many electrons
Electrified Object
The object that behaves as a reservoir for stray electric charges
Electric Ground
The electrostatic force is directly proportional to the product of the electrostatic charges & inversely proportional to the square of the distance between them
Coulomb’s Law
Coulomb’s Law formula
F = k(QaQb/d2)
— Where:
o F = electrostatic force (N)
o k = constant of proportionality (9x109 coulomb-meter)
o Qa & Qb = charges (Coulomb)
o d = distance (m2)
The lines of force that causes charged particles to move from one pole to another
Electric Field
Under electric field, where do positive and negatice charges point to?
Positive charge: points outward
Negative charge: points toward
Unlike charges attract; Like charges repel
REPULSION-ATTRACTION
— do not have an electric field
Uncharged particles
Electric field — from positive charge
radiates out
Electric field — a negative charge
radiate toward
4 concepts under Electrostatic laws
- Distribution
- Law of Conceentration
- Electrostatic force
- Movement
Charges uniformly distributed at the surface
Distribution
Sharpest curvature of a surface
Law of concentration
The force of attraction between unlike charges or repulsion between like charges
Electrostatic force
Where is electrostatic forve inverssely and directly proportional to?
▪ Directly proportional to the product of their charges
▪ Inversely proportional to the square of the distance between them
Under movement, only — move along the solid conductors
negative charges
Under movemtn, — are tightly bound inside the nucleus
protons
The study of electric charges in motion
Electrodynamics
Works with electric current
Electrical Engineer
Concerned with electron flow
Physicist
Movement electrons along the wire
Electric Current
Two Types of Current
Direct Current
Alternating Current (60Hz)
Differentiate direct and alternating current in terms of description and waveform
Direct current: Electrons that flow in only one direction
Waveform: straight line
Alternating current: Electrons that flow alternately in the oppositedirection
Waveform: sinusoidal
4 states of electric current
- conductor
- insulator
- semiconductor
- superconductor
Any substance through which electrons flow easily
Conductor
Any material that does not allow electron flow
Insulator
A material that some conditions behave as an insulator & as a conductor
Semiconductor
Any material that allows electrons to flow without resistance
Superconductor
Characteristics of a conductor
▪ Variable resistance
▪ Obeys Ohm’s law
▪ Requires voltage
▪ Examples: copper (Z=29), aluminum (Z=13) & water
Characteristics of an insulator
▪ Does not permit electron flow
▪ Extremely high resistance
▪ Necessary with high voltage
▪ Examples: glass, rubber & clay
Characteristics of a semiconductor
▪ Can be conductive
▪ Can be resistive
▪ Basis for computers
▪ Examples: silicon (Si-14) & germanium (Ge-32)
Characteristics of a superconductor
▪ No resistance to electron flow
▪ No electric potential required
▪ Must be very cold
▪ Examples: niobium (Nb-41) & titanium (Ti-22)
He demonstrated semiconduction
William Shockley (1946)
The property of some matter to exhibit no resistance below a critical temperature
Superconductivity (1911)
A pathway that permits electrons to move in a complete circle from their source through the various components & back again
Electric circuits
The flow of electrons through a conductor
Electric Current/Electricity
Direction of an Electric Current/Electricity
Always opposite the electron flow
How is electric current measured?
Amperes (A)
Electric Current/Electricity
1A = ?
1 A: 1 C/s or 1 electric charge/second
How is electric potential measured?
Volts
Electric Potential
1 V = ?
1 V: 1 J/C or 1 potential energy/unit charge
How is electric resistance measured?
Ohms
Under electric circuits:
More (1)→ the greater the (2)→ (3)
- complex
- resistance
- decrease the electric current
The voltage across the total circuit or any portion of the circuit is equal to the current times the resistance
Ohm’s Law
Formulas for Ohm’s Law
▪ V = IR (for voltage)
▪ R = V/I (for resistance)
▪ I = V/R (for current)
2 Basic Types of Electric Circuit
- SERIES CIRCUIT
- PARALLEL CIRCUIT
All circuit elements are connected in a line along the same conductor
Series circuit
RULES for SERIES:
o Rt = R1 + R2+ R3
o It = I1 = I2 = I3
o Vt = V1 + V2+ V3
Elements are connected at their ends rather than lying in a line along a conductor
Parallel circuit
Rule for Rt (Parallel circuit)
1/Rt = 1/R1 + 1/R2 + 1/R3
