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Module 03 Electrical 100 important sentences for Revision

October 25, 2025 Aircraft, easa, Electrical, Module 3

1. Basic Electrical Terms

Electricity is the flow of electrons through a conductor.
Electric current is the rate of flow of charge.
The unit of current is the ampere (A).
Voltage is the electrical pressure that causes current flow.
The unit of voltage is the volt (V).
Resistance opposes the flow of electric current.
The unit of resistance is the ohm (Ω).
Power is the rate of doing electrical work.
The unit of electrical power is the watt (W).
Energy equals power multiplied by time.

2. Electric Charge and Current

Electric charge is measured in coulombs (C).
One coulomb equal one ampere-second.
Electrons have negative charge and move in conductors.
Conventional current flows from positive to negative.
Electron flow direction is opposite to conventional current.
Static electricity is charge at rest.
Conductors allow free movement of electrons.
Insulators resist electron movement.
Semiconductors conduct under certain conditions only.
Electric current requires a complete circuit to flow.

3. Ohm’s Law and Circuits

Ohm’s law: V = I × R.
If voltage increases, current increases proportionally.
Current decreases when resistance increases.
Series circuit current is same in all components.
Parallel circuit voltage is same across all branches.
Total resistance in series equals sum of all resistors.
Total resistance in parallel is always less than smallest resistor.
Kirchhoff’s voltage law states sum of voltages in a loop equals zero.
Kirchhoff’s current law states sum of currents entering a junction equals sum leaving.
Power formula: P = V × I.

4. Electrical Power and Energy

Electrical energy measured in watt-hours or kilowatt-hours.
One kilowatt-hour equals 3.6 million joules.
Efficiency equals output power divided by input power.
Power loss in resistor equals I² × R.
Electric fuse protects circuit by melting under overcurrent.
Circuit breaker opens automatically when current exceeds limit.
Switch controls current flow manually.
Ammeter connected in series measures current.
Voltmeter connected in parallel measures voltage.
Ohmmeter measures resistance of circuit components.

5. Magnetism and Electromagnetism

Magnetic materials attract iron, nickel, and cobalt.
Magnetic field lines travel from north to south outside magnet.
Magnetic flux is total number of magnetic field lines.
Unit of magnetic flux is the weber (Wb).
Magnetic flux density equals flux divided by area.
Unit of flux density is the tesla (T).
Right-hand rule shows direction of magnetic field around conductor.
Electromagnetism is magnetic effect produced by current.
Solenoid converts electrical energy into magnetic field.
Relays and contactors operate using electromagnetic coils.

6. Electromagnetic Induction

Electromagnetic induction produces voltage by changing magnetic field.
Faraday’s law states induced emf proportional to rate of flux change.
Lenz’s law states induced emf opposes cause producing it.
Self-induction occurs when current change induces emf in same coil.
Mutual induction occurs between two coils placed close together.
Inductance is ability to oppose change in current.
Unit of inductance is henry (H).
Energy stored in inductor equals ½ L × I².
Induced voltage polarity always opposes current change.
Alternators generate AC voltage using electromagnetic induction.

7. Capacitance

Capacitor stores electric charge and energy in electric field.
Capacitance equals charge divided by voltage (C = Q/V).
Unit of capacitance is farad (F).
Dielectric material increases capacitor’s storage ability.
Series capacitance total is less than smallest capacitor.
Parallel capacitance total equals sum of all capacitances.
Energy stored in capacitor equals ½ C × V².
Capacitor blocks DC but passes AC signals.
Electrolytic capacitors are polarized and used in DC circuits.
Ceramic capacitors are non-polar and used in AC circuits.

8. Alternating Current (AC)

Alternating current changes direction periodically.
AC waveform is usually sinusoidal.
Frequency is number of cycles per second in hertz (Hz).
Period is time taken for one complete cycle.
Amplitude is maximum value of AC voltage or current.
RMS value equals 0.707 × peak value for sine wave.
Average value equals 0.637 × peak value.
Phase angle is difference in phase between two AC waveforms.
In pure resistance, current and voltage are in phase.
In inductive circuit, current lags voltage by 90 degrees.

9. Inductive and Capacitive Reactance

Inductive reactance (XL) = 2πfL.
Capacitive reactance (XC) = 1 / (2πfC).
Reactance opposes change in AC current flow.
Impedance (Z) is total opposition to AC, combining resistance and reactance.
Impedance formula: Z = √(R² + (XL − XC)²).
Power factor = cosine of phase angle between current and voltage.
Power factor = true power divided by apparent power.
Lagging power factor indicates inductive load.
Leading power factor indicates capacitive load.
Correction capacitors improve lagging power factor.

10. Transformers and Power Systems

Transformer transfers electrical energy between circuits by magnetic induction.
Primary winding receives input voltage.
Secondary winding delivers output voltage.
Turns ratio determines voltage transformation ratio.
Step-up transformer increases voltage and reduces current.
Step-down transformer decreases voltage and increases current.
Transformer efficiency equals output power divided by input power.
Core losses include hysteresis and eddy current losses.
Isolation transformer separates two circuits for safety.
Autotransformer uses common winding for both primary and secondary.

Aircraft Electrical System Basic Knowledge

October 21, 2025 Aircraft, Electrical, Electrical System Basic Knowledge

The Aircraft Electrical System is one of the most important systems in an aircraft — it provides, distributes, and controls electrical power for all the aircraft’s components and systems.

⚙️ 1. Purpose of Electrical System

The aircraft electrical system provides power to:

Avionics (radios, navigation systems)
Lights (interior & exterior)
Instruments
Flight control systems
Engine starting system
Cabin systems (air conditioning, entertainment, etc.)
Emergency systems (backup power, warning lights)

⚡ 2. Types of Electrical Power

Aircraft use two main types of current:

Type	Description	Common Uses
DC (Direct Current)	Flows in one direction	Battery, starter motor, some avionics
AC (Alternating Current)	Changes direction periodically	High-power systems like de-icing, lights, and large avionics

🔋 3. Power Sources

Main sources of electricity in aircraft:

Battery – Supplies DC power when engines are off or as backup.
Alternator/Generator – Driven by the engine or APU; converts mechanical energy to electrical energy.
Auxiliary Power Unit (APU) – A small engine that generates electrical power when the main engines are off.
Ground Power Unit (GPU) – External power source used on the ground to save fuel.