Capacitance

My friend Justus asked these two questions:

1. What is capacitance?
2. What are conduits?

Let's discuss Capacitance first.
Capacitance is a term to do with capacitors, it is the ability of a Capacitor to store electric charge when its plates are at different potentials. 
Capacitance is measured in Farads. A Farad is the Capacitance of a capacitor which requires a potential difference of 1 volt to maintain the charge of 1 coulomb on that capacitor.

Capacitance (C) = Charge (Q)/p.d across capacitor (volts). 

Making Q the subject brings us to the term 'Electric Charge'. This is the potential difference of the capacitance of the capacitor and the applied voltage.
Q = CV

Electrolytic Capacitors

There are other smaller units of capacitance:

1µF = 10^-6 F

1nF = 10^-9 F

1pF =10^-12 F

What is a Capacitor? Still somebody else perhaps my friend might want to know what a Capacitor is.
A Capacitor is a device that has ability to store electric charge. It consists of two conductive plates separated by a dielectric which prevents charge from moving between the plates directly.
Capacitors are divided into two groups:

1. Fixed Capacitors
2. Variable Capacitors 

Unlike fixed capacitors, the capacitance value of variable capacitors can be altered. 

Capacitor symbols

In Fixed capacitor group, we have subcategories and these include:

• Non polarised capacitor. This type of capacitor can be connected either way. It has no positive pole or negative pole.
• Polarised capacitor. The polarised type have positive and negative terminal and must be connected so that there's Direct Current through it in the correct direction. A capacitor of this kind is electrolytic that is it has an electrolyte in between its plates as a dielectric. 

Variable capacitors are also subdivided into two groups:

1. Tuning capacitors. These are used in radio receivers, Television and Transmitter circuit for tuning.
2. Trimmers. These are used to make a fine tune in the circuit. The symbol for trimmers is a bit different.

 

Symbol for Trimmer capacitor

 Capacitors can also be divided into five groups according to their dielectric:

• Paper Capacitor. This capacitor consists of two metal foils with a waxed paper in between them.
• Air capacitors. These are used in radio receivers for tuning. They consist one set of fixed plates and another set of movable plates.
• Mica Capacitor. In this capacitor, mica is the dielectric seperating two plates. Mica capacitors are used in high frequence circuits.
• Ceramic Capacitor. A capacitor of this kind is made up of ceramic material like clay. It is also used in high frequence circuits for variation of temperature.
• Electrolytic Capacitor. This capacitor is made up of Aluminium foils with an oxide film. Capacitors of this kind can be used for power factor improvement in machines.

Capacitors in an electronic circuit

 

Symbol for Electrolytic Capacitor

 Capacitors are also used in power distribution to improve power factor.



Conduit System is a wiring system, read the post 'Wiring Systems: Conduits'.