Capacitor Tutorial Summary

Capacitor Tutorial Summary

• A capacitor consists of two metal plates separated by a dielectric.
• The dielectric can be made of many insulating materials such as air, glass, paper, plastic etc.
• A capacitor is capable of storing electrical charge and energy.
• The higher the value of capacitance, the more charge the capacitor can store.
• The larger the area of the plates or the smaller their separation the more charge the capacitor can store.
• A capacitor is said to be "Fully Charged" when the voltage across its plates equals the supply voltage.
• The symbol for electrical charge is Q and its unit is the Coulomb.
• Electrolytic capacitors are polarized. They have a +ve and a -ve terminal.
• Capacitance is measured in Farads, which is a very large unit so micro-Farad ( uF ), nano-Farad ( nF ) and pico-Farad ( pF ) are generally used.
• Capacitors that are daisy chained together in a line are said to be connected in Series.
• Capacitors that have both of their respective terminals connected to each terminal of another capacitor are said to be connected in Parallel.
• Parallel connected capacitors have a common supply voltage across them.
• Series connected capacitors have a common current flowing through them.
• Capacitive reactance is the opposition to current flow in AC circuits.
• 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: