Capacitor

A capacitor is a passive two-terminal electrical component that stores electrical energy in an electric field. A capacitor consists of two or more parallel conductive (metal) plates which are not connected or touching each other, but are electrically separated either by air or by Dielectric.

capacitor-types

Capacitor Symbols

capacitor-dielectric

Capacitor Dielectric

When there is potential difference across the conductors, (e.g. when a capacitor is connected across a battery) an electric field develops across the dielectric, causing positive charge +Q to collect on one plate and negative charge -Q on other plate. If a battery has been attached to a capacitor for a sufficient amount of time, no current can flow through the capacitor. However, if a time varying voltage is applied across the leads of capacitor, a displacement current can flow.

The SI unit of Capacitance is farad (F).

Capacitance is defined as the ratio of the electric charge Q on each conductor to the potential difference V between them.

C = Q / V.

C -> Capacitance (Farads)
Q -> Charge (Coulombs)
V -> Voltage (Volts)

capacitors-in-series

Capacitors in Series

Capacitors are said to be connected in "series", when they are daisy chained in a single line. The charging current (iC) flowing through the capacitors is same for all capacitors as it has only one path to flow.

The total capacitance, CTotal of the series capacitor circuit must be equal to the reciprocal sum of all the individual capacitors added together. Therefore

1/CTotal = 1/C1 + 1/C2 + ... + 1/Cn.

capacitors-in-parallel

Capacitors in Parallel

Capacitors are said to be connected in "parallel", when both of their terminals respectively connected to each terminal of the other capacitors. Capacitors connected in parallel have common voltage across them.

The total capacitance, CTotal of the parallel capacitor circuit must be equal to the sum of all the individual capacitors added together. Therefore

CTotal = C1 + C2 + ... + Cn.