Electromagnetics

Electricity

An invisible force that can produce heat, light, motion, and other physical effects seen in various applications.

Bohr's Atomic Theory

States that an atom resembles a miniaturized solar system with electrons, protons, and neutrons.

Static Electricity

Electricity generated when charges are at rest, often produced by friction between different materials. Also called FRICTIONAL ELECTRICITY

Dynamic Electricity

Electricity generated when charges are in motion or transferring between atoms, known as ELECTRIC CURRENT.

Charge

Basic unit is Coulomb (C), where 1 Coulomb equals 6.28x10^18 electrons.

Current

Charge in motion/ Flow of free electrons, measured in Amperes (A), where 1 ampere equals 1 coulomb/second.

Voltage (Electromotive Force)

Source of electrons causing their motion, measured in Volts (V), potential energy difference that exist across two point w/c tend to cause a flow of electrons

Resistance

Property limiting current flow in a circuit, material, or substance, converting electrical energy to heat, measured in Ohms (Ω).

RESISTANCE LAW

The resistance of a conducting material is proportional to it's length and inversely proportional to it's cross sectional area

Circular Mil (CM)

Unit of area for circular wires

Conductance

Reciprocal of resistance, measuring how fast electrons pass through a material, in Siemens (S).

Electrical Power

Work done per unit time in a circuit, measured in Watts (W), where 1 watt equals 1 Joule/second.

Work or Energy

Accomplishment of motion against opposing force, base unit is Joule (J), performed whenever an energy id converted from one form to another, xxwhere 1 Joule equals 1 Watt-second.

Coulomb's Law of Electrostatics

Calculates force between charges, stating that unlike charges attract and like charges repel.

Energy Stored in Electric Circuit

Energy density in an electric circuit, measured in Joules/m^3.

Electric Flux Density

Measure of electric flux per unit area, also known as Charge Density, measured in Coulombs/m^2.

Permittivity

Measure of how easily a dielectric permits flux lines or charge, ratio of electric flux density to electric field strength, measured in Farad/meter.

Conductors

Materials allowing free electron travel.

Less than 4 VE

Insulators

Materials preventing electricity flow,

More than 4

Semiconductors

Materials with electrical characteristics between conductors and insulators.

4 VE

Magnetism

A natural phenomenon where some materials are attracted by magnets.

Electromagnetism

Magnetism generated by an electric current instead of natural magnets.

Magnet

A material that attracts iron, steel, nickel, or cobalt.

Magnetic Field

The area around a magnet where magnetic flux lines are present.

Natural magnets

permanent magnets

Artificial Magnets

created by electromagnetism can be either temporary or permanent magnets

Retentivity

The property of magnetic materials allowing residual magnetism.

Residual Magnetism

Magnetism remaining after removing the magnetizing force.

Coercive Force

Force needed to eliminate residual magnetism and counter retentivity.

Magnetic Flux

Total magnetic lines of force in a magnetic field.

Magnetic Flux Density

Flux per unit area of a magnetic material.

Magnetomotive Force (MMF)

Creates magnetic flux in a circuit, measured in Ampere-turns.

Magnetic Field Strength or Intensity

Region where magnetic materials experience a magnetic force.

Reluctance

Opposition to establishing magnetic flux, measured in At/Wb.

Permeance

Measure of a magnetic circuit's ability to allow flux. reciprocal of reluctance

Coulomb's Law of Electromagnetism

Law stating the force between magnetic poles is proportional to their strengths.

COULOMB'S 2ND LAW

the force of attraction or repulsion of the two poles is inversely proportional to the square of the distance r b/w them

Magnitude of Force in a Current Carrying Conductor

Force experienced by a conductor carrying current in a magnetic field.

Magnitude of Force Between Two Parallel Conductors

Force between two parallel conductors carrying currents.

Energy Stored in Magnetic Circuits

Energy stored in a magnetic circuit due to magnetic flux.

Hysteresis Loss (Steinmetz's Formula)

Heat loss due to magnetic hysteresis in magnetic circuits.

Permeability

Material's ability to allow flux, ratio of flux density to field intensity.

Ferromagnetic Materials

Materials strongly attracted by magnets (μr >>> 1).

Paramagnetic Materials

Materials slightly attracted by intense magnetic fields (μr slightly > 1).

Diamagnetic Materials

Materials slightly repelled by intense magnetic fields (μr slightly < 1).

Non-Magnetic Materials

Materials with no magnetic effect such as air (μr = 1).

Capacitance

Measure of capacitor's ability to store charge on its plates. Basic unit is Farad (F).

Farad

Basic unit of capacitance, symbolized as F.

Spherical Capacitor

Capacitor with a capacitance formula 𝐶= 4𝜋𝜀𝑜𝜀𝑟𝑅, where R is the radius of the spherical capacitor.

Inductance

Measure of ability to store energy in the form of a magnetic field. Base unit is Henry (H).

Henry

Base unit of inductance, symbolized as H.

Mutual Inductance

Measure of inductive coupling between two coils, formula is 𝑀= 𝑘𝐿1 ∙𝐿2.

Transformer

Device transferring electric energy from one circuit to another, with primary and secondary windings.

Self-Inductance

Voltage induced in a coil related to the current flowing in the same coil.

Electromagnetic Induction

Production of an Electromotive Force (EMF) due to a change in the magnetic field.

Capacitive Coupling

Transfer of electrical energy between circuits using displacement current induced by an electric field.

Magnetic/Inductive Coupling

Transfer of electrical energy between circuits due to change in current creating a change in voltage through electromagnetic induction.

Faraday's Law

States that the induced electromotive force (EMF) in any closed circuit is equal to the rate of change of magnetic flux through the circuit.

Coupling Coefficient

A measure of the coupling between two coils, mathematically expressed as the mutual inductance divided by the square root of the product of the self-inductances of the two coils.

Dot Convention

A notation used in magnetically coupled circuits to determine the polarity of the induced voltage, represented by a dot mark at the end of coils in the circuit.

Lenz's Law

States that the direction of the induced electromotive force (EMF) in a circuit is such that it opposes the change in magnetic flux that produces it.

Faraday's Second Law

States that the magnitude of the induced EMF in a circuit is equal to the rate of change of flux linkages with the circuit, mathematically expressed as 𝑉= −𝑁𝑑𝜙/𝑑𝑡.

Stationary Loop in a Time-Varying B Field

Refers to the situation where a time-varying current induces EMF in a stationary loop, often termed as transformer EMF in power analysis.

Motional EMF

The induced electromotive force in a loop moving in a static magnetic field, represented by the equation 𝐸𝑚= 𝑣× 𝐵.

Maxwell's Equations

A set of four fundamental equations in electromagnetism describing how electric and magnetic fields are generated and altered by each other and by charges and currents.

Gauss's Law for Static Electric Fields

States that the total electric displacement flux through a closed surface is equal to the total charge inside the surface.

Gauss's Law for Static Magnetic Fields

States that the total magnetic flux passing through any closed surface is zero.

Faraday's Law of Induction

States that an electromotive force (EMF) is induced around a closed path due to a changing magnetic field.

Ampere's Circuit Law

States that the magnetomotive force around a closed path is equal to the sum of electric displacement and conduction currents through any surface bounded by the path.

RESISTANCE LAW

“The resistance of a conducting material is directly proportional to its length (R R∝L) and inversely proportional to its cross sectional area (R R∝1 /A)