EASA Module 3 study guide
EASA Module 3 · Work through your exam, one topic at a time.
EASA Module 3, Electrical Fundamentals, is one of the basic knowledge modules that a candidate must pass to qualify for an aircraft maintenance licence under the European Part-66 licensing system, in the B1 (mechanical) and B2 (avionics) categories. It is a theory module rather than a type course: it builds the physics foundation - electron theory, static electricity and conduction, electrical terminology, generation of electricity, DC sources and circuits, resistance and power, capacitance, magnetism, inductance, DC motor and generator theory, and finally AC theory including resistive, capacitive and inductive circuits, transformers, filters, AC generators and AC motors - that later modules on aircraft electrical systems, instruments and avionics assume you already hold. The EASA Module 3 study guide has 12 sections and about 5,063 words.
01Electron Theory
All electrical behaviour stems from atomic structure: a nucleus of protons (positive) and neutrons (neutral) surrounded by electrons (negative) arranged in shells. The number of protons defines the element; the electron arrangement defines electrical behaviour.
280 words, about 1 min02Static Electricity and Conduction
Static electricity is charge at rest, produced by triboelectric separation - rubbing dissimilar materials transfers electrons so one surface becomes positive and the other negative. Charge resides on the outer surface of a conductor and distributes so that the internal field is zero (the Faraday cage effect).
309 words, about 2 min03Electrical Terminology
Current (ampere) is the rate of charge flow, I = Q/t; one ampere is one coulomb per second. Electromotive force (emf) is the energy per unit charge supplied by a source; potential difference is the energy per unit charge converted by a load.
305 words, about 2 min04Generation of Electricity
Electricity is generated by converting other forms of energy: friction (static), pressure (piezoelectric crystals), heat (thermocouple, Seebeck effect), light (photovoltaic cell), chemical action (cells) and magnetism (electromagnetic induction, the source of virtually all aircraft power). Faraday's law: an emf is induced in a conductor whenever it experiences a changing magnetic flux.
293 words, about 1 min05DC Sources of Electricity
A cell converts chemical energy into electrical energy using two dissimilar electrodes in an electrolyte. Primary cells (alkaline, zinc-carbon, silver oxide) are not rechargeable; secondary cells (lead-acid, NiCd, NiMH, lithium-ion) are.
312 words, about 2 min06DC Circuits
Ohm's law V = IR holds for a resistive element at constant temperature. Parallel : the same voltage appears across each branch, currents add, 1/R total = 1/R₁ + 1/R₂ + ..., and the total is always less than the smallest branch.
302 words, about 2 min07Resistance, Resistors and Power
R = ρl/A: resistance rises with length and resistivity, and falls with cross-sectional area. Copper and aluminium are the standard conductors; nickel-chrome alloys make heating elements.
298 words, about 1 min08Capacitance and Capacitors
Two conductors separated by a dielectric store charge: C = Q/V, measured in farads (F). For a parallel-plate capacitor, C = ε₀ε r A/d - larger area or higher permittivity raises capacitance, greater separation lowers it.
341 words, about 2 min09Magnetism
A current produces a magnetic field; a coil concentrates it. Flux Φ (weber) is the total field through an area; flux density B (tesla) is flux per unit area, B = Φ/A.
307 words, about 2 min10Inductance and Inductors
Inductance is the property of a circuit that opposes a change of current by producing a back emf. L = NΦ/I, in henries.
340 words, about 2 min11DC Motor/Generator Theory
A current-carrying conductor in a magnetic field experiences a force F = BIl (times sin θ for angle). This is motor action: force produces torque, and the commutator reverses the coil current every half turn to keep torque in one direction.
345 words, about 2 min12AC Theory, Resistive/Capacitive/Inductive Circuits, Transformers, Filters, AC Generators and AC Motors
AC varies sinusoidally: v = V p sin(2πft). Period T = 1/f; frequency in hertz.
1,631 words, about 8 min