Capacitor Tutorial Summary

1.     A capacitor consists of two metal plates separated by a dielectric.

2.     The dielectric can be made of many insulating materials such as air, glass, paper, plastic etc.

3.     A capacitor is capable of storing electrical charge and energy.

4.     The higher the value of capacitance, the more charge the capacitor can store.

5.     The larger the area of the plates or the smaller their separation the more charge the capacitor can store.

6.     A capacitor is said to be "Fully Charged" when the voltage across its plates equals the supply voltage.

7.     The symbol for electrical charge is Q and its unit is the Coulomb.

8.     Electrolytic capacitors are polarized. They have a +ve and a -ve terminal.

9.     Capacitance is measured in Farads, which is a very large unit so micro-Farad (uF), nano-Farad (nF) and pico arad (pF) are generally used.

10.    Capacitors that are daisy chained together in a line are said to be connected in Series.

11.    Capacitors that have both of their respective terminals connected to each terminal of another capacitor are said to be connected in Parallel.

12.    Parallel connected capacitors have a common supply voltage across them.

13.    Series connected capacitors have a common current flowing through them.

14.    Capacitive reactance is the opposition to current flow in AC circuits.

15.    In AC capacitive circuits the voltage "lags" the current by 90^o.

The basic construction and symbol for a parallel plate capacitor is given as: