Basic Electrical and Electronics Engineering Principles

Key Notes on Units

• Prefixes matter:

  • milli (m) =

    ${10}^{-3}$

    , micro (μ) =

    ${10}^{-6}$

    , nano =

    ${10}^{-9}$

    .

  • Example: 1 mA = 0.001 A, 1 μF =

    ${10}^{-6}$

    F.

• Derived relationships:

  • Ohm’s Law:

    $V=I\cdot R$

    .

  • Power:

    $P=V\cdot I$

    .

  • Energy:

    $E=P\cdot t$

    .

• Practical ranges:

  • Household voltage: 120–240 V.

  • Small electronics: 1–12 V.

  • Typical resistors: 1 Ω – 1 MΩ.

  • Capacitors: picofarads (pF) to millifarads (mF).

⚠️ Important Considerations

• Measurement tools:

  • Current → Ammeter (series).

  • Voltage → Voltmeter (parallel).

  • Resistance → Ohmmeter.

  • Power → Wattmeter.

• Safety: High voltage and current can be dangerous. Even small currents (above ~30 mA) can be harmful to humans.

• Applications:

  • Capacitance: energy storage, filtering, timing circuits.

  • Inductance: transformers, motors, filters.

  • Frequency: critical in AC systems and communication.

✅ In summary: Ampere, Volt, Ohm, and Watt form the foundation of electrical measurement, while Coulomb, Farad, Henry, Siemens, Joule, and Hertz extend the framework to cover charge, energy storage, magnetism, and oscillations. These units are interconnected through fundamental laws like Ohm’s Law and energy-power relationships.