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08 – Polarised Capacitor

The picture shows a sketch of a Polarised Capacitor on the left and the symbol on the right.

A capacitor consists of two conducting plates with an isolation material called a dielectric between them. The conducting plates can be aluminium discs, aluminium foil or a thin film of metal. When a potential difference like a battery is applied to the two different plates of the capacitor electricity flows into the plates and they are charged up until they are at the same potential as the battery. When the battery is removed the capacitor retains it’s charged up state for a while until the charge slowly leaks away. Capacitance is measured in Farads but a Farad is a very big unit and most capacitors are in the Micro Farad and Pico Farad range.

A Polarised Capacitor’s plates are polarity sensitive and are normally electrolytic and tend to be bigger than normal non-polarised capacitors.

Capacitors are used in various electronic applications, here are a few examples:

  1. Smoothing voltage ripples.
  2. In RC filter applications.