Electromagnetism & Electronics — 67 Terms Defined

Faraday's Law of Induction Electromagnetism & Electronics V (Volts) Maxwell's third equation stating that a time-varying magnetic flux through a closed conductive loop induces an electromotive force (EMF) around the loop. E = -dΦ_B / dt, ∇ × E = -∂B/∂t

Ferromagnetism Electromagnetism & Electronics Dimensionless A strong magnetic phenomenon in which atomic magnetic moments spontaneously align parallel into localized magnetic domains, producing permanent magnetization. μ_r ≫ 1 (μ_r ~ 1,000–100,000)

Gauss's Law for Electricity Electromagnetism & Electronics N·m²/C (or V·m) Maxwell's first equation stating that the net electric flux through any closed Gaussian surface equals the total enclosed charge divided by vacuum permittivity. Φ_E = ∮ E · dA = Q_enclosed / ε₀, ∇ · E = ρ / ε₀

Gauss's Law for Magnetism Electromagnetism & Electronics Wb (Webers) Maxwell's second equation stating that the total magnetic flux passing through any closed surface is always identically zero. Φ_B = ∮ B · dA = 0, ∇ · B = 0

Hall Effect Electromagnetism & Electronics V (Hall Voltage), m³/C (Hall Coefficient) The production of a transverse electric potential difference (Hall voltage) across a current-carrying conductor in an orthogonal magnetic field. V_H = (I B) / (n q t), R_H = 1 / (n q)

Inductive Reactance Electromagnetism & Electronics Ω (Ohms) The opposition offered by an inductor to alternating current flow, directly proportional to AC frequency and inductance. X_L = 2π f L = ω L

Joule Heating Electromagnetism & Electronics J (Joules) The process in which the flow of electric current through a conductor generates thermal energy due to electrical resistance. H = I² R t = P t

Kirchhoff's Laws Electromagnetism & Electronics A (Current), V (Voltage) Two fundamental circuit analysis laws expressing conservation of electric charge (Current Law) and conservation of energy (Voltage Law). KCL: ∑ I_in = ∑ I_out; KVL: ∑ V = 0

LC Circuit & Oscillations Electromagnetism & Electronics Hz (Frequency), J (Energy) An electrical circuit containing an inductor and capacitor that exchanges energy periodically between the electric field of the capacitor and magnetic field of the inductor. f₀ = 1 / (2π √(L C)), E_total = ½ C V² + ½ L I²

Lenz's Law Electromagnetism & Electronics Dimensionless (Directional Law) A physical law asserting that the direction of an induced current always produces a magnetic field that opposes the change in magnetic flux that induced it. Represented by the negative sign in E = -dΦ_B/dt

Logic Gates Electromagnetism & Electronics Binary (0 or 1) Elementary digital electronic building blocks that perform Boolean logical operations on one or more binary inputs to yield a single binary output. AND: Y = A·B; OR: Y = A + B; NOT: Y = Ā; NAND: Y = (A·B)̄

Lorentz Force Electromagnetism & Electronics N (Newtons) The combined force exerted on a charged particle moving through electromagnetic fields containing both electric and magnetic field components. F = q (E + v × B)

Magnetic Dipole Electromagnetism & Electronics A·m² (or J/T) The basic magnetic structure created by a closed circulating current loop or intrinsic particle spin, possessing North and South magnetic poles. μ = I A, τ = μ × B

Magnetic Dipole Moment Electromagnetism & Electronics A·m² (or J/T) A vector quantity determining the torque experienced by a magnetic dipole when placed in an external magnetic field. μ = I A, U = -μ · B

Magnetic Field Electromagnetism & Electronics T (Tesla = N/(A·m)) A vector field generated by moving electric charges, electric currents, or intrinsic magnetic moments that exerts magnetic forces on other moving charges and dipoles. F_mag = q (v × B), B = μ₀ I / (2π r)

Magnetic Flux Electromagnetism & Electronics Wb (Webers = T·m²) The measure of the total magnetic field passing normally through a specified surface area. Φ_B = ∫ B · dA = |B| |A| cos θ

Magnetic Hysteresis Electromagnetism & Electronics J/m³ (Joules per cubic meter) The lagging of magnetization behind the applied magnetizing field in ferromagnetic materials during cyclic magnetization. Hysteresis Loss Area = ∫ H dB

Magnetic Permeability Electromagnetism & Electronics H/m (or T·m/A) A material property measuring the degree to which a medium supports and concentrates magnetic flux inside itself when subjected to a magnetic field. μ = B / H = μ_r μ₀, μ₀ = 4π × 10⁻⁷ T·m/A

Magnetic Susceptibility Electromagnetism & Electronics Dimensionless A dimensionless material property measuring the degree of magnetization induced in a material per unit applied magnetic field strength. M = χ_m H, μ_r = 1 + χ_m

Maxwell's Equations Electromagnetism & Electronics Various SI Units The set of four fundamental partial differential equations that unify electricity, magnetism, and optics into classical electrodynamics. ∇·E = ρ/ε₀, ∇·B = 0, ∇×E = -∂B/∂t, ∇×B = μ₀J + μ₀ε₀∂E/∂t

MOSFET Electromagnetism & Electronics A (Current) A Metal-Oxide-Semiconductor Field-Effect Transistor that uses an insulated gate voltage to control current flow through an underlying semiconductor channel. I_D = ½ μ_n C_ox (W/L) (V_GS - V_th)²

Moving Coil Galvanometer, Ammeter & Voltmeter Electromagnetism & Electronics A (Current), V (Voltage) An electromechanical instrument that measures small currents using magnetic torque on a pivoted coil, converted to an ammeter or voltmeter using shunts or series resistors. τ = N I A B = k θ; Ammeter: S = I_g G / (I - I_g); Voltmeter: R_s = (V / I_g) - G

Mutual Inductance Electromagnetism & Electronics H (Henries) The induction of an electromotive force in a secondary circuit loop caused by a time-varying current in an adjacent primary circuit loop. E₂ = -M (dI₁/dt), M = k √(L₁ L₂)

Ohm's Law Electromagnetism & Electronics V = A · Ω An empirical relation stating that the electric current flowing through an ohmic conductor is directly proportional to the applied voltage and inversely proportional to resistance. V = I R, J = σ E