Understanding Capacitors and Their Applications

Oct 2, 2024

Lecture Notes: Capacitors

Introduction

  • Presenter: Paul from TheEngineeringMindset.com
  • Topic: Understanding capacitors, their functions, usage, and importance.
  • Safety Warning: Electricity is dangerous. Only qualified individuals should handle electrical work. Capacitors can cause electric shocks; do not touch terminals.

What is a Capacitor?

  • Function: Stores electric charge, similar to a battery but operates differently.
  • Energy Storage:
    • Cannot store as much energy as a battery.
    • Charges and discharges energy much faster.
  • Usage: Found in almost every circuit board.

How Does a Capacitor Work?

  • Analogy: Compared to a water tank in a pipe system:
    • Water tank stores water to smooth interruptions.
    • Capacitor stores energy to smooth electrical supply interruptions.
  • Circuit Behavior:
    • Without capacitor: Circuit interrupts cause light to flash.
    • With capacitor: Light remains on during interruptions as capacitor discharges.

Internal Structure

  • Components:
    • Two conductive metal plates (e.g., aluminum).
    • Separated by dielectric insulating material (e.g., ceramic).
  • Dielectric Function: Polarizes in electric field, contributing to energy storage.

Charging Process

  • Connection: One side to positive, other to negative circuit sides.
  • Electron Flow: Electrons build on one plate, creating potential difference (voltage).
  • Measurement: Voltage can be measured with a multimeter.

Discharging Process

  • Electron Attraction: Opposite charges attract but are separated by dielectric.
  • Electric Field: Holds electrons in place until another path is made.
  • Circuit Use: Capacitor powers circuit during power supply interruptions.

Applications of Capacitors

  • In Circuit Boards: Identifiable via specific symbols.
  • Larger Capacitors: Used in applications such as induction motors, ceiling fans, air conditioning units.
  • Power Factor Correction:
    • Aligns current and voltage waveforms in large buildings.
    • Uses capacitor banks.
  • AC to DC Conversion:
    • Smooths out power supply when converting AC to DC using rectifiers.

Measuring Capacitors

  • Capacitance: Measured in farads (F), usually in microfarads (µF).
  • Voltage Rating: Indicates maximum voltage handling, measured in volts (V).
    • Exceeding voltage can cause explosion.

Using a Multimeter

  • Voltage Measurement:
    • Ensure it's discharged before handling.
  • Capacitance Measurement:
    • Connect to multimeter's capacitor function.

Safety and Precautions

  • Capacitors store energy and can hold charge even when disconnected.
  • Always discharge capacitors before handling.

Conclusion

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