Electron Theory & Static Electricity
Not publishedof exam
Atomic StructureCoulomb's LawEMF vs PDGeneration MethodsConductors vs Insulators
DC Sources of Electricity
Not publishedof exam
Primary vs Secondary CellsLead-Acid BatteryNiCd BatteryInternal ResistanceSeries vs Parallel Cells
DC Circuits Ohm's & Kirchhoff's Laws
Not publishedof exam
Ohm's LawCurrent Law KCLVoltage Law KVLSeries CircuitsParallel Circuits
Resistance, Resistors & Power
Not publishedof exam
Colour CodeResistivityWheatstone BridgePower FormulasThermistors
Capacitance & Capacitors
Not publishedof exam
C = Q/VRC Time ConstantSeries vs Parallel CStored EnergyDielectric Factors
Magnetism, Inductance & DC Machines
Not publishedof exam
Faraday's LawLenz's LawLR Time ConstantBack EMFRight-Hand Rule
AC Theory, Transformers & Machines
Not publishedof exam
RMS 0.707 PeakReactance XL and XCResonanceTransformer RatioStar vs Delta
Quick Facts
- Exam
- EASA Module 3
- Credential
- Part-66 B1/B2 licence
- Questions
- 52 (Cat B1/B2)
- Time
- 65 min (B1/B2)
- Pass mark
- 75%
- Format
- 3-option MCQ
- Level
- Level 1-2 knowledge
- Blueprint
- Reg (EU) 2023/989
EMF vs Potential Difference
EMF
- Open-circuit voltage
- Total source energy
- Drives the current
PD
- Voltage under load
- Across one component
- Less than EMF
Source vs load voltage
Atomic & Static Basics
- Electron
- Negative charge carrier
- Proton
- Positive, in nucleus
- Coulomb's law
- F = kQ1Q2/d-squared
- Charge unit
- Coulomb (C)
- Current unit
- Ampere (A)
- EMF
- Open-circuit driving voltage
- Potential difference
- Voltage under load
- Conventional flow
- Positive to negative
Conductors, Insulators & Generation
- Conductor
- 1-3 valence electrons
- Insulator
- 5-8 valence electrons
- Semiconductor
- 4 valence electrons
- Thermocouple
- Heat to EMF
- Photovoltaic cell
- Light to EMF
- Piezoelectric effect
- Pressure to EMF
- Triboelectric effect
- Friction makes static charge
Cells & Batteries
- Primary cell
- Not rechargeable
- Secondary cell
- Rechargeable
- Lead-acid electrolyte
- Sulphuric acid
- NiCd electrolyte
- Potassium hydroxide
- Series cells
- EMF adds together
- Parallel cells
- Capacity adds together
- Terminal voltage
- EMF minus internal drop
- Specific gravity
- Checks lead-acid charge state
Series vs Parallel Circuits
Series
- Current common
- Resistances add
- Voltage divides
Parallel
- Voltage common
- Total below smallest
- Current divides
Common current vs common voltage
Series vs Parallel Quick Rules
- Need total R in series→Add all resistances
- Need total R, 2 parallel→Product over sum
- Need total R, N equal parallel→Divide by N
- Need one branch current→Ohm's law that branch
- Need one component's drop→V = I x R there
Ohm's & Kirchhoff's Laws
- Ohm's law
- V = I x R
- Current form
- I = V/R
- Resistance form
- R = V/I
- KCL
- Sum of currents at node = 0
- KVL
- Sum EMF = sum drops
- Series rule
- Current common, voltage divides
- Parallel rule
- Voltage common, current divides
- Voltage divider
- V2 = V x R2/Rtotal
Resistor Colour Sequence
Black Brown Red Orange Yellow Green Blue Violet Grey White
Gold band means 5%Silver band means 10%No band means 20%
NTC vs PTC Thermistor
NTC
- Resistance falls with heat
- Used for sensing
PTC
- Resistance rises with heat
- Used for protection
Falls vs rises with heat
Resistor Colour Code
- Black
- Digit 0
- Brown
- Digit 1
- Red
- Digit 2
- Orange
- Digit 3
- Yellow
- Digit 4
- Green
- Digit 5
- Blue
- Digit 6
- Violet
- Digit 7
- Gold band
- Plus-minus 5% tolerance
- Silver band
- Plus-minus 10% tolerance
Power Triangle
Power equals VI, or I-squared R, or V-squared over R
VI: voltage x currentI-squared R: current squared x RV-squared/R: voltage squared / R
Resistance & Power Formulas
- Resistivity
- R = rho x L/A
- Temp coefficient (metal)
- Resistance rises with heat
- NTC thermistor
- Resistance falls with heat
- PTC thermistor
- Resistance rises with heat
- Potentiometer
- 3-terminal variable divider
- Wheatstone balance
- R1/R2 = R3/R4
- Power formula 1
- P = V x I
- Power formula 2
- P = I-squared x R
- Power formula 3
- P = V-squared/R
- Energy
- W = P x t
RC Time Constant Rule
Tau equals R times C; five tau is full charge
1 tau equals 63%5 tau is near fullDischarge mirrors the charge curve
Series vs Parallel Capacitors
Series C
- Product over sum
- Total value drops
Parallel C
- Values simply add
- Total value rises
Opposite of resistor rule
RC Circuit Quick Rules
- Need series C total→Product over sum formula
- Need parallel C total→Add all capacitances
- Need near-full charge time→Allow 5 time constants
- Need charge at 1 tau→63% of supply
- DC steady state, no current→Capacitor acts as open
Capacitance Fundamentals
- Capacitance
- C = Q/V
- Unit
- Farad (F)
- Series capacitors
- Product over sum, like parallel R
- Parallel capacitors
- Values simply add
- RC time constant
- Tau = R x C
- Full charge
- About 5 time constants
- One time constant
- 63% charged
- Stored energy
- W = half C V-squared
- Higher permittivity
- Capacitance increases
- Wider plate gap
- Capacitance decreases
LR Time Constant Rule
Tau equals L over R for inductive circuits
L in henriesR in ohmsSame 63%, 5-tau pattern
Self vs Mutual Inductance
Self inductance
- One coil only
- Opposes its own change
Mutual inductance
- Two linked coils
- Induces EMF in other
One coil vs two coils
Magnetism & Inductance Selector
- Need field direction→Right-hand grip rule
- Need induced current direction→Lenz's law
- Need induced EMF size→Faraday's law, rate of change
- Need LR time constant→Tau = L/R
- Need motor force direction→Fleming's left-hand rule
- Need generator EMF direction→Fleming's right-hand rule
Magnetism & Electromagnetism
- External flux direction
- North pole to south pole
- Ferromagnetic metals
- Iron, nickel, cobalt
- Right-hand grip rule
- Field around a conductor
- Reluctance
- Opposition to magnetic flux
- Hysteresis
- Flux lags magnetising force
- Remanence
- Retained magnetism after removal
- Flux density unit
- Tesla
- MMF
- Current x turns
Inductance & DC Machines
- Faraday's law
- EMF proportional to flux change rate
- Lenz's law
- Induced current opposes the change
- Inductance unit
- Henry
- Mutual inductance
- Linked coils induce EMF
- LR time constant
- Tau = L/R
- Coupling coefficient 1
- Perfect mutual coupling
- Commutator
- Converts generator AC to DC
- Back EMF
- Opposes armature current
- Fleming's left hand
- Motor force direction
- Series motor
- High starting torque
CIVIL AC Phase Rule
CIVIL: Capacitor I leads V, Inductor V leads I
Capacitor: current leadsInductor: voltage leads400 Hz aircraft AC
Inductor vs Capacitor Phase
Inductor
- Current lags voltage
- Reactance rises with frequency
Capacitor
- Current leads voltage
- Reactance falls with frequency
CIVIL mnemonic
AC Filter & Reactance Selector
- Need pass low, block high→Low-pass filter
- Need pass high, block low→High-pass filter
- Need pass one band only→Band-pass filter
- Need reject one band only→Band-stop filter
- Need XL at higher frequency→Reactance increases
- Need XC at higher frequency→Reactance decreases
AC Waveform Basics
- RMS value
- 0.707 x peak
- Average value
- 0.637 x peak
- Form factor
- About 1.11
- Periodic time
- T = 1/f
- Aircraft AC
- 400 Hz standard
- Capacitive circuit
- Current leads voltage 90 degrees
- Inductive circuit
- Current lags voltage 90 degrees
- Moving-coil meter
- Reads average/DC only
Star vs Delta Connection
Star (wye)
- Line V = root3 phase V
- Line I = phase I
Delta
- Line V = phase V
- Line I = root3 phase I
Voltage factor vs current factor
Reactance, Impedance & Resonance
- Inductive reactance
- XL = 2 pi f L
- Capacitive reactance
- XC = 1/(2 pi f C)
- XL with frequency
- Increases
- XC with frequency
- Decreases
- Resonance condition
- XL = XC
- Impedance
- Z = root of R-squared+X-squared
- Power factor
- Cos phi = R/Z
- Skin effect
- Current crowds toward surface
Transformers & Filters
- Turns ratio
- Vp/Vs = Np/Ns
- Ideal transformer
- Vp x Ip = Vs x Is
- Eddy current fix
- Laminated core
- Hysteresis loss fix
- Soft magnetic core material
- Low-pass filter
- Passes low frequencies
- High-pass filter
- Passes high frequencies
- Band-pass filter
- Passes one band only
- Band-stop filter
- Rejects one band only
Three-Phase & AC Machines
- Phase spacing
- 120 degrees apart
- Star line voltage
- Root3 x phase voltage
- Delta to star
- Divide resistance by 3
- Slip
- Sync speed minus rotor speed
- Synchronous speed
- Sets sync motor speed
- Squirrel-cage rotor
- No slip rings needed
- Single-phase induction motor
- Not self-starting alone
- Reverse 3-phase motor
- Swap any two leads
Common Traps
Conventional vs Electron Current Flow
Conventional: positive to negative ≠ Electron: negative to positive
Series R vs Series C Formula
Series R: simply add values ≠ Series C: product over sum
Capacitor vs Inductor at DC Steady State
Capacitor: acts as open circuit ≠ Inductor: acts as short circuit
Reactance vs Frequency Direction
XL rises as frequency rises ≠ XC falls as frequency rises
Star vs Delta Line Voltage
Star: line V = root3 phase ≠ Delta: line V = phase V
Resistor Tolerance Colour Meaning
Gold band means plus-minus 5% ≠ Silver band means plus-minus 10%
Self vs Mutual Inductance Scope
Self: one coil's own field ≠ Mutual: linked separate coils
Real Exam vs Practice Bank Options
Real EASA exam uses 3 options ≠ This practice bank uses 4
Last Minute
- 1.52 questions in 65 minutes
- 2.75% pass mark, no negative marking
- 3.Real exam uses three answer options
- 4.Ohm's law: V = I R
- 5.Series: current common, resistances add
- 6.Parallel: voltage common, current divides
- 7.RC time constant: tau = RC
- 8.LR time constant: tau = L/R
- 9.RMS equals 0.707 times peak value
- 10.Resonance: XL equals XC
- 11.Aircraft AC frequency is 400 Hz
- 12.Gold band tolerance equals plus-minus 5%
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