EASA Module 3 Exam Flashcards

Q: How many questions are on EASA Part-66 Module 3 and how much time do I get?

For licence categories B1 and B2, Module 3 is examined by 52 multiple-choice questions in 65 minutes. Category A candidates sit a shorter 20-question paper in 25 minutes. The real exam uses 3-option multiple-choice questions, unlike the 4-option format used in most practice question banks.

Q: What is the pass mark for EASA Module 3?

Every EASA Part-66 module, including Module 3, has a 75% pass mark. There is no partial credit and no negative marking for wrong answers, so it always pays to attempt every question.

Q: What happens if I fail Module 3, and how soon can I retake it?

A failed module exam cannot be retaken for at least 90 days. You get a maximum of three consecutive attempts; if all three fail, a 12-month waiting period applies before you can start a new set of three attempts at any EASA-approved examination centre.

Q: Is Module 3 mostly calculations or definitions?

It is a mix of both. Expect direct recall questions on terminology, colour codes and unit names alongside numerical questions requiring Ohm's law, power, capacitive/inductive reactance and resonance calculations, so both memorisation and calculation practice matter.

Q: Why do these flashcards weight some topics more heavily than others if EASA does not publish official topic weights?

EASA's syllabus (Commission Implementing Regulation (EU) 2023/989) lists Module 3's subject areas but does not publish scoring weights for each one. This deck allocates more cards to AC theory/transformers and magnetism/inductance because those areas cover the most distinct sub-topics in the syllabus, matching the topic distribution used in this site's Module 3 practice question bank.

Question 1

Electron

Accepted Answer

The subatomic particle carrying a single negative charge; it orbits the nucleus in shells, and its movement between atoms is what constitutes electric current.

Question 2

Proton and Neutron

Accepted Answer

Both reside in the atom's nucleus: the proton carries a positive charge (balancing the atom's electrons), while the neutron carries no charge at all and adds mass only.

Question 3

Valence Electron Count Rule

Accepted Answer

The number of electrons in an atom's outer (valence) shell predicts its conductivity: 1-3 valence electrons = good conductor, 4 = semiconductor, 5-8 = insulator.

Question 4

Coulomb's Law

Accepted Answer

F = k x Q1 x Q2 / d-squared - the force between two charged bodies is directly proportional to the product of their charges and inversely proportional to the square of the distance between them.

Question 5

EMF vs. Potential Difference (PD)

Accepted Answer

EMF is the open-circuit voltage generated by the source itself; PD is the voltage measured across a component once current is flowing. PD is always less than EMF because some voltage is lost across the source's own internal resistance.

Question 6

Conventional Current vs. Electron Flow

Accepted Answer

Conventional current is defined as flowing from the positive terminal to the negative terminal; the actual electrons physically move the opposite way, from negative to positive. Circuit diagrams and Fleming's rules use conventional flow.

Question 7

Six Ways to Generate an EMF

Accepted Answer

Friction (triboelectric/static charge), pressure (piezoelectric effect), heat (thermocouple/Seebeck effect), light (photovoltaic cell), chemical action (battery), and magnetism (electromagnetic induction).

Question 8

Triboelectric Effect

Accepted Answer

Rubbing two dissimilar materials together transfers electrons between them, leaving one surface positively charged and the other negatively charged - the basis of static electricity buildup, which is why aircraft are bonded/grounded during refuelling.

Question 9

Primary vs. Secondary Cell

Accepted Answer

A primary cell's chemical reaction is not reversible, so it cannot be recharged and is discarded once flat. A secondary cell's reaction is reversible, so it can be recharged and reused many times.

Question 10

Lead-Acid vs. Nickel-Cadmium Electrolyte

Accepted Answer

Lead-acid uses dilute sulphuric acid, and its specific gravity (checked with a hydrometer) reliably indicates state of charge. NiCd uses potassium hydroxide, and - unlike lead-acid - its specific gravity stays essentially constant regardless of charge state, so it cannot be used to judge charge.

Question 11

Cells in Series vs. Parallel

Accepted Answer

Connecting cells in series adds their EMFs together (same current capacity as one cell); connecting cells in parallel adds their current capacity together (same EMF as one cell). Either way, terminal voltage = EMF minus (current x internal resistance), so it sags under load.

Question 12

Ohm's Law

Accepted Answer

V = I x R. Rearranged: I = V/R to find current, or R = V/I to find resistance - the three forms needed for every DC circuit calculation.

Question 13

Kirchhoff's Current Law (KCL)

Accepted Answer

The sum of currents flowing into a junction equals the sum of currents flowing out of it - current is conserved at every node, with zero net current accumulating there.

Question 14

Kirchhoff's Voltage Law (KVL)

Accepted Answer

Around any closed loop, the sum of the EMFs equals the sum of the voltage drops - energy supplied by sources in a loop is fully accounted for by the drops across its components.

Question 15

Series Circuit Rule

Accepted Answer

Current is the same at every point (only one path exists); total resistance is the simple sum of all resistors; supply voltage divides across components in proportion to their resistance (voltage divider: V2 = V x R2/Rtotal).

Question 16

Parallel Circuit Rule

Accepted Answer

Voltage is the same across every branch; current divides between the branches; total resistance is always less than the smallest branch resistance (1/Rtotal = 1/R1 + 1/R2 + ...; for two resistors, use product over sum).

Question 17

Resistor Colour Code - Digits

Accepted Answer

Each colour band represents a digit: Black 0, Brown 1, Red 2, Orange 3, Yellow 4, Green 5, Blue 6, Violet 7, Grey 8, White 9 - read the first bands as significant digits, then apply the multiplier band.

Question 18

Resistor Tolerance Bands

Accepted Answer

The final band states manufacturing tolerance: Gold = plus/minus 5%, Silver = plus/minus 10%, no band = plus/minus 20%. A tighter tolerance means the actual resistance is guaranteed closer to the printed value.

Question 19

Resistivity Formula

Accepted Answer

R = (rho x L) / A - a conductor's resistance rises with its length (L) and its material's resistivity (rho), and falls as its cross-sectional area (A) increases.

Question 20

NTC vs. PTC Thermistor

Accepted Answer

An NTC (negative temperature coefficient) thermistor's resistance falls as it heats up, useful for temperature sensing. A PTC (positive temperature coefficient) thermistor's resistance rises as it heats up, useful for overcurrent/overheat protection.

Question 21

Wheatstone Bridge Balance Condition

Accepted Answer

A four-arm resistance bridge is balanced (zero galvanometer deflection) when R1/R2 = R3/R4 - this ratio lets an unknown resistor be measured precisely against three known ones.

Question 22

Power and Energy Formulas

Accepted Answer

Power can be found three ways depending on what you know: P = V x I, P = I-squared x R, or P = V-squared / R. Energy consumed over time is W = P x t.

Question 23

Capacitance Formula

Accepted Answer

C = Q/V, measured in farads (F) - capacitance is the amount of charge (Q) a capacitor stores per volt (V) applied across its plates.

Question 24

Factors Affecting Capacitance

Accepted Answer

Capacitance increases with larger plate area and higher dielectric permittivity between the plates, and decreases as the plate separation (gap) increases.

Question 25

Capacitors in Series vs. Parallel

Accepted Answer

This is the opposite of the resistor rule: capacitors in series combine like parallel resistors (total value drops, product-over-sum for two), while capacitors in parallel simply add together (total value rises).

Question 26

RC Time Constant

Accepted Answer

Tau = R x C. After one time constant, a charging capacitor reaches about 63% of the supply voltage; after roughly five time constants it is considered fully charged. Stored energy is W = half x C x V-squared.

Question 27

External Magnetic Flux Direction

Accepted Answer

Outside a magnet, magnetic flux lines run from the north pole to the south pole (they continue through the magnet's interior from south back to north, forming a closed loop).

Question 28

Right-Hand Grip Rule

Accepted Answer

Grip a current-carrying conductor with your right hand, thumb pointing in the direction of conventional current flow - your curled fingers show the direction of the magnetic field circling the conductor.

Question 29

Reluctance and Magnetomotive Force (MMF)

Accepted Answer

Reluctance is a magnetic circuit's opposition to flux, the magnetic equivalent of electrical resistance. MMF, the driving force that pushes flux through a circuit, equals current x number of turns, measured in ampere-turns.

Question 30

Hysteresis and Remanence

Accepted Answer

Hysteresis is the lag between a changing magnetising force and the resulting flux density in a core. Remanence is the magnetism a core retains after the magnetising force has been removed to zero.

Question 31

Faraday's Law of Induction

Accepted Answer

The EMF induced in a conductor or coil is proportional to the rate of change of magnetic flux linkage - move a conductor through a field faster, or change the field faster, and more EMF is generated.

Question 32

Lenz's Law

Accepted Answer

An induced current always flows in the direction that opposes the change in flux that created it - this is why induced effects resist motion and conserve energy, and it sets the sign in Faraday's law.

Question 33

Self vs. Mutual Inductance

Accepted Answer

Self inductance is a single coil opposing changes in its own current (unit: henry). Mutual inductance is two magnetically linked coils, where a changing current in one induces an EMF in the other.

Question 34

LR Time Constant

Accepted Answer

Tau = L/R for an inductive circuit - current builds toward its final value following the same 63%-at-one-tau, near-full-at-five-tau pattern as an RC circuit's voltage.

Question 35

DC Motor and Generator Rules

Accepted Answer

Fleming's left-hand rule gives the force (and rotation) direction in a motor; Fleming's right-hand rule gives the induced EMF direction in a generator. A motor's back EMF opposes the applied armature current, limiting it as speed rises; a generator's commutator converts the AC induced in the rotating armature into DC output.

Question 36

RMS Value of an AC Waveform

Accepted Answer

RMS (root-mean-square) value = 0.707 x peak value for a sine wave. It represents the equivalent DC value that delivers the same heating/power effect, which is why AC voltages and currents are normally quoted as RMS.

Question 37

Average Value of an AC Waveform

Accepted Answer

Average value (over a half cycle) = 0.637 x peak value. The ratio of RMS to average, called the form factor, works out to about 1.11 for a pure sine wave.

Question 38

Periodic Time

Accepted Answer

T = 1/f - periodic time is the time for one complete cycle of an AC waveform, and is simply the reciprocal of frequency.

Question 39

Standard Aircraft AC Frequency

Accepted Answer

Most aircraft AC electrical systems run at 400 Hz rather than 50/60 Hz mains frequency, because the higher frequency allows transformers, motors and generators to be built smaller and lighter for a given power rating.

Question 40

Phase Relationship in a Purely Capacitive Circuit

Accepted Answer

In a capacitor, current leads voltage by 90 degrees - the capacitor must charge (current flows) before its voltage can rise to follow.

Question 41

Phase Relationship in a Purely Inductive Circuit

Accepted Answer

In an inductor, current lags voltage by 90 degrees - the coil's back EMF opposes the immediate build-up of current as the applied voltage first rises. Remember 'CIVIL': in a Capacitor, I leads V; in an Inductor, V leads I.

Question 42

Inductive Reactance (XL)

Accepted Answer

XL = 2 x pi x f x L - an inductor's opposition to AC current rises as frequency increases, because faster current changes induce a larger opposing back EMF.

Question 43

Capacitive Reactance (XC)

Accepted Answer

XC = 1 / (2 x pi x f x C) - a capacitor's opposition to AC current falls as frequency increases, because it has less time to fully charge and discharge each cycle.

Question 44

Series RLC Resonance Condition

Accepted Answer

Resonance occurs when XL equals XC, cancelling each other out so the circuit's impedance drops to its minimum value (just R) and current is at its maximum for a given applied voltage.

Question 45

Impedance and Power Factor

Accepted Answer

Impedance Z equals the square root of (R-squared plus X-squared), combining resistance and net reactance. Power factor = cos(phi) = R/Z, showing how much of the apparent power actually does useful (real) work.

Question 46

Skin Effect

Accepted Answer

At higher AC frequencies, current tends to crowd toward the outer surface of a conductor rather than flow evenly through its whole cross-section, which increases the conductor's effective resistance.

Question 47

Transformer Turns Ratio

Accepted Answer

Vp/Vs = Np/Ns - the ratio of primary to secondary voltage matches the ratio of primary to secondary turns. For an ideal transformer, power is conserved, so Vp x Ip = Vs x Is, meaning a step-up in voltage means a step-down in current, and vice versa.

Question 48

Transformer Core Losses

Accepted Answer

Eddy current loss comes from circulating currents induced within the core itself, and is reduced by using a laminated (thin, insulated-sheet) core. Hysteresis loss comes from repeatedly re-magnetising the core each cycle, and is reduced by choosing a soft magnetic core material with a narrow hysteresis loop.

Question 49

AC Filter Types

Accepted Answer

A low-pass filter passes frequencies below its cutoff; a high-pass filter passes frequencies above its cutoff; a band-pass filter passes only a range between two cutoffs; a band-stop (notch) filter rejects only that range.

Question 50

Star (Wye) vs. Delta Three-Phase Connections

Accepted Answer

In a star connection, line voltage = root-3 x phase voltage while line current equals phase current. In a delta connection, line voltage equals phase voltage while line current = root-3 x phase current.

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EASA Part-66 Module 03 — Electrical Fundamentals

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