Midterms | Unit 2.1 Electricity Flashcards by Eun Woo

Electricity and Magnetism are manifestations of a single underlying —

electromagnetic force

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Converts electric energy into electromagnetic energy

X-ray Imaging System

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X-ray Imaging System’s primary function

Converts electric energy into electromagnetic energy

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Differentiate Electrostatics and Electrodynamics

Electrostatics is the study of stationary electric charges.

Electrodynamics is the study of electric charges in motion

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The study of the distribution of fixed charges

Electrostatics

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Types of electric chrages

Electric Potential (V)
Electric Current (I)

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Electric Potential is measured in —

Volt

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Electric current is measured in —

Ampere

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Potential energy per unit charge

Volt

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One Coulomb of electric charge
flowing per second

Ampere

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Relation of Volt to electric charge

Volt is potential energy per unit charge (1 V = 1 J/C)

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Relation of Ampere to electric charge

Ampere is one Coulomb of electric charge flowing per second (1 A = 1 C/s)

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Smallest units of electricity

Electron and proton

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Fundamental unit (S.I)

Coulomb

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1 C= ?

10^18 electron chrages

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Transfer or movement of an electron from one object to another object.

Electrification

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Electrification can be created in what ways?

Friction
Contact
Induction

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When one object is rubbed against another

Friction

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When two object touch, permitting electrons to move from one to the other

Contact

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The process of electrical fields acting on another without contact

Induction

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Most important method (used in the operation of electronic devices)

Induction

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If object has too few or too many electrons

Electrified Object

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The object that behaves as a reservoir for stray electric charges

Electric Ground

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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

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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)

1. complex 2. resistance 3. 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

Midterms | Unit 2.1 Electricity Flashcards

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